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Title Page
1 File System Manager Administrator window ... 27
2 About dialog box... 31
3 EMC Centera C-Clip for a DiskXtender file ... 44
4 Embedded BLOB for a file stored on EMC Centera... 47
5 Separate CDF and BLOB for a file stored on EMC Centera... 48
6 Single thread per piece of virtual media... 50
7 Simultaneous moves and fetches... 51
8 Random migration to EMC Centera... 52
9 Media service wizard - Centera Information page ... 60
10 Options for automatic creation of EMC Centera media... 62
11 Tiered migration... 77
12 DiskXtender with NAS... 81
13 DiskXtender connection with MediaStor ... 92
14 Single DiskXtender server connecting to a single MediaStor server... 93
15 Single DiskXtender server connecting to multiple MediaStor servers ... 94
16 Multiple DiskXtender servers sharing a MediaStor server... 95
17 MediaStor Administrator... 100
18 DiskXtender with ACSLS... 103
19 Available Media tree... 114
20 Media group Automation page ... 118
21 Compact media task ... 120
22 Format media task after Compact media task ... 120
23 Label media task after Compact and Format media tasks... 121
24 DiskXtender with TSM... 134
25 DiskXtender with cloud storage ... 145
26 Disabling real-time moves ... 171
27 Standard migration ... 176
28 Multi-target migration... 176
29 Multi-target media group ... 177
30 Sample file migration pattern for multi-target migration... 178
31 Tiered migration... 180
32 DiskXtender architecture for indexing... 203
33 Disabling real-time moves ... 205
34 Indexing attributes on the DiskXtender File Properties dialog box ... 206
35 Disabling index rule qualification ... 214
36 Disabling the indexing schedule... 215
37 Promote/demote arrow buttons... 252
38 Media Properties dialog box... 253
Title Page
1 Supported removable media types... 23
2 Supported DiskXtender environments for License Server ... 35
3 Types of retention ... 54
4 Supported CenteraStar versions ... 58
5 Best practices for EMC Centera media service options ... 61
6 Extended drive operations for EMC Centera files ... 68
7 NAS media types... 76
8 Extended drive operations for Standard NAS files... 84
9 Extended drive operations for aggregate NAS files ... 84
10 Extended drive operations for retained NAS files ... 85
11 Minimum and recommended hardware requirements for MediaStor ... 98
12 Supported removable media types... 110
13 FIle system support by media type ... 112
14 Subsystems for the OTG file system... 112
15 UDF file systems... 113
16 Status of media in the Available Media tree ... 114
17 Extended drive operations for files migrated to MO and UDO media... 124
18 Extended drive operations for files migrated to MO WORM or UDO WORM media 125 19 Extended drive operations for files migrated to tape or tape-WORM media... 125
20 Extended drive operations for files migrated to DVD media... 126
21 Media group options for removable media ... 128
22 Service options for optical and tape media ... 131
23 DiskXtender edits for TSM dsm.opt file ... 135
24 Extended drive operations for TSM files ... 139
25 Extended drive operations for files migrated to cloud media... 149
26 Product interoperability and international character support ... 154
27 Background scan tasks ... 164
28 Scan maintenance options... 165
29 Available criteria for selecting files to move ... 173
30 Recommended media group options for each media type... 186
31 Types of retention ... 192
32 Retention editing options... 198
33 Icons for files on the extended drive ... 220
34 Prerequisite steps for purging... 221
35 Purge process overview by purge method... 222
36 Recommended environments for each purge method ... 223
37 Available criteria for selecting files to purge ... 224
38 File recovery requirements by media type... 240
40 Media status indicated by color... 251
41 Media Properties dialog box tabs... 254
42 Reports ... 257
43 Available events for audit logging... 259
44 Access to the audit log for DiskXtender security groups ... 260
45 Audit log fields ... 260
46 Recommended media protection methods... 265
47 Compatible media types for copy media ... 277
48 File recovery requirements by media type ... 285
49 Media support for moving files within a media folder ... 293
50 DiskXtender edits for TSM dsm.opt file... 305
51 Extended drive options to adjust for a storage transition ... 309
As part of an effort to improve and enhance the performance and capabilities of its product lines, EMC periodically releases revisions of its hardware and software. Therefore, some functions described in this document may not be supported by all versions of the software or hardware currently in use. For the most up-to-date information on product features, refer to your product release notes.
If a product does not function properly or does not function as described in this document, please contact your EMC representative.
Audience This document is part of the EMC DiskXtender for Windows documentation set, and is intended for use by system administrators responsible for installing software and maintaining the servers and clients on a network.
Readers of this document are expected to be familiar with the following topics:
◆ Microsoft Windows network administration
◆ Storage media and hardware device management
Related documentation
Related documents include:
◆ EMC DiskXtender Release 6.5 SP 7 Microsoft Windows Version Installation Guide ◆ EMC DiskXtender Release 6.5 SP 7 Microsoft Windows Version Release Notes ◆ EMC DiskXtender Release 6.5 SP 7 Microsoft Windows Version Utilities Guide
Conventions used in this document
EMC uses the following conventions for special notices.
Note: A note presents information that is important, but not hazard-related.
CAUTION
!
A caution contains information essential to avoid data loss ordamage to the system or equipment.
IMPORTANT
!
Where to get help EMC support, product, and licensing information can be obtained as follows:
Product information —For documentation, release notes, software updates, or information about EMC products, go to EMC Online Support at:
https://support.emc.com
Technical support —Go to EMC Online Support and click Service Center. You will see several options for contacting EMC Technical Support. Note that to open a service request, you must have a valid support agreement. Contact your EMC sales
representative for details about obtaining a valid support agreement or with questions about your account.
Your comments Your suggestions will help us continue to improve the accuracy, organization, and overall quality of the user publications. Please send your opinion of this document to: [email protected]
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• Names of interface elements (such as names of windows, dialog boxes, buttons, fields, and menus)
• Names of resources, attributes, pools, Boolean expressions, buttons, DQL statements, keywords, clauses, environment variables, functions, utilities • URLs, pathnames, filenames, directory names, computer names, filenames, links,
groups, service keys, file systems, notifications
Bold Used in running (nonprocedural) text for:
• Names of commands, daemons, options, programs, processes, services, applications, utilities, kernels, notifications, system call, man pages Used in procedures for:
• Names of interface elements (such as names of windows, dialog boxes, buttons, fields, and menus)
• What user specifically selects, clicks, presses, or types Italic Used in all text (including procedures) for:
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Courier Used for:
• System output, such as an error message or script
• URLs, complete paths, filenames, prompts, and syntax when shown outside of running text
Courier bold Used for:
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• Variables on command line • User input variables
< > Angle brackets enclose parameter or variable values supplied by the user [ ] Square brackets enclose optional values
The following topics provide an introduction to and describe the benefits of EMC® DiskXtender® for Windows:
◆ Seamless extension of disk space ... 20
◆ Automated file management... 22
Seamless extension of disk space
DiskXtender for Windows is so named because it extends the amount of space on a server’s local New Technology File System (NTFS) and Resilient File System (ReFS) volumes, or hard drive partition. This can either be a volume physically located on the DiskXtender server or a fibre-connected drive that has been mapped as a local drive.
DiskXtender extends the amount of space on a drive by migrating files from the drive to external storage media, while maintaining the appearance that the files are still on the drive. A drive that has been extended through DiskXtender is called an extended drive.
The management of files on the extended drive through DiskXtender is actually a two-part process. Those two parts are referred to as a move and a purge and can be performed separately or simultaneously.
In DiskXtender, a move is actually a copy. When DiskXtender moves a file to media, it is really copying the file data out to media and adding extended attribute information to the file on the drive. The file is then managed by DiskXtender, and the data resides both on the extended drive and on the media.
After file data is moved to storage media, that data can be removed, or purged, from the extended drive, which frees that space for additional files. The purging of a file removes the file data from the drive, and leaves behind a file tag on the drive. The data then resides only on the media.
The file tag serves two purposes:
◆ It allows the file to appear as if it still resides on the drive so that users can easily find it.
◆ It contains the extended file attribute information that DiskXtender needs to manage and retrieve the file from media.
To a user who retrieves files from a drive extended by DiskXtender, all files appear to be present, regardless of whether the file data is on the drive or only on storage media. When the user requests the files, DiskXtender accesses the media where the files are stored and retrieves the file data, and displays it for the user. This file retrieval process is called a fetch.
Full NTFS compatibility
Since DiskXtender uses the NTFS file system as the gateway to its remote storage management functions, all native features of NTFS are supported, including support for:
◆ Long filenames (up to 256 characters)
◆ Filenames with Unicode characters
◆ Folder and file-level security
◆ Offline files
Regardless of the media type that is being used for remote storage, full security can be applied to any file or folder on an extended drive, even if the storage media itself does not support Microsoft Windows security (for example, magneto-optical WORM or tape).
ReFS compatibility
Apart from NTFS, DiskXtender is also compatible with ReFS. While DiskXtender uses extended attributes to store migration information in NTFS, it uses reparse tags in ReFS. You can extend (or archive data) from both NTFS as well as ReFS volumes. All the DiskXtender functionality supported on NTFS (apart from incremental scan) is supported on ReFS.
Native Windows network connectivity and security
DiskXtender does not interfere with Windows networking. Users that access an extended drive, usually through network shares, can connect by using any installed transports and protocols.
Automated file management
DiskXtender automates the migration of files to media by using a rule-based system. Rather than just migrate all files to media without distinction between the files, you can select which files should be moved to what types and pieces of media, and when those files are moved.
After file data is moved to storage media, automatic file purge options can remove the file data from the drive, and leave behind a file tag so that the file can be retrieved when necessary.
File purging can occur:
◆ Immediately for all files, as soon as they are moved to media
◆ When extended drive disk space is needed
◆ When the files meet other criteria, such as a certain age
If necessary, you can protect migrated files from being edited or deleted during a specified time period. This protection is called file retention, and is required in some environments to comply with government and organizational regulations. Retention is available if you are migrating files from DiskXtender to one of the following devices:
◆ EMC Centera®
◆ EMC Celerra® with the File-Level Retention (FLR) file system
◆ Network Appliance (NetApp) NAS device with SnapLock software
When you apply retention, the files are protected both on the extended drive and on the storage hardware device.
In some instances, you may also want to delete files completely when they are no longer of use. You can either delete files manually (for example, through Windows Explorer), or you can delete files automatically through DiskXtender by using rule-based criteria.
Flexible support for back end storage
DiskXtender supports many high-capacity storage media types, including several removable media and disk-based storage options.
Table 1 on page 23 provides details on the supported removable media types.
These media types are supported through a wide variety of hardware devices. For a complete list, refer to the DiskXtender for Windows Supported Device List, available on EMC Online Support.
Disk-based storage options include EMC CLARiiON®, Celerra, EMC Isilon®, EMC
VNX/VNXe® series, as well as many other Redundant Array of Independent Disks
(RAIDs) and network-attached storage (NAS) devices. Essentially, a server with a network share that is available to DiskXtender can be used as storage media. DiskXtender considers all of these shared devices to be NAS media.
DiskXtender also supports the use of an EMC Centera content-addressed storage (CAS) system, the first magnetic disk-based WORM device. DiskXtender and EMC Centera are tightly integrated to optimize file storage and retrieval performance. Several DiskXtender file migration and retention features are designed specifically to take advantage of the features available with an EMC Centera device.
DiskXtender works effectively with the highly scalable virtual media delivered by the cloud storage system. The cloud media is elastic, enabling you to use as much media as your data demands. DiskXtender allows for file migration to both private as well as public cloud systems. DiskXtender supports the use of EMC Atmos.
DiskXtender transparently manages data movement between the extended drive and the storage media. Communication with the hardware devices that contain the storage media is established through the creation of DiskXtender media services. DiskXtender transfers files to the media provided by the media services, and sends requests for pieces of media to the media services as needed.
DiskXtender manages all functions related to the transfer of information to and from media, such as the migration and retrieval of files. The only role a media service plays is to provide access to the media so that DiskXtender can work with it.
◆ For a media service that provides access to removable media, this means that the service places the requested media into a drive or prompts the administrator of the media service to insert the appropriate piece of media.
◆ For a media service that provides access to disk-based devices, this means that the service provides access to a place where the data is written.
You can use any or all of these media types with a single DiskXtender installation.
Hardware
scalability
With DiskXtender, hardware can grow with your storage needs, and you do not need to reconfigure or reformat the extended drives. DiskXtender interfaces with the software that manages the storage devices. The devices are completely independent Table 1 Supported removable media types
Media type Details
Tape and tape-WORM LTO, SDLT, DLT, SAIT, AIT, 9840, and 9940
DVD DVD-R, DVD-RAM, and DVD-ROM
of the extended drives they support, even though DiskXtender controls the media in those devices. If you are using removable media, you can change hardware and relocate media without affecting the files on your extended drive or the ability of DiskXtender to find files on the storage media.
DiskXtender stores an internal inventory of all online and offline media in the system. This inventory system means that removable media is not dedicated to a specific hardware device. When hardware configuration or removable media locations change, the internal inventory is automatically updated so that DiskXtender always knows where media is located.
When file migration or retrieval is required, DiskXtender uses its internal inventory to automatically find the proper media for the requested file.
Automated media
management
DiskXtender can automatically prepare media for file migration when it is needed, as well as reclaim space that is no longer used on some media types.
If you are using removable media, DiskXtender can automatically format, label, and assign media for file migration from a group of blank media. You can also reclaim space on removable media by compacting it when wasted space exceeds a certain percentage. When you compact a piece of media, active files on the media (current versions of written files and files not marked for deletion) are written back to the extended drive and are remigrated to another piece of eligible media. You can then reformat the compacted media so that it can be used again. Compaction optimizes media usage even if file deletions are frequent.
If you are using an EMC Centera device, DiskXtender can automatically create the "virtual" media that DiskXtender uses to simulate divisions of an EMC Centera cluster. The use of virtual media enables you to take advantage of the flexible file migration features available in DiskXtender.
If you are using the cloud media, you can add EMC Atmos as a media service and create virtual media. EMC Atmos provides the big advantage of flexible media, that expands depending on your file migration needs.
If you are using DVD-R media, DiskXtender can automatically finalize the media when it is full. Finalization closes the media, which prevents the writing of any more files to the media. Finalization also increases the stability of the media so that data is better protected.
Offline media
support
Offline media support is very important for large systems with limited hardware resources and large storage requirements. DiskXtender fully supports offline media. With DiskXtender, media can be online or offline. When online, users can access any file on the media. If media is taken offline and a file is requested that is not on the extended drive, the user receives an error message and the DiskXtender system administrator is notified that the requested media must be mounted.
One important benefit of DiskXtender offline media support is that the files on your extended drive are not affected by the state of the media. Unlike other products, where files disappear when media is taken offline, DiskXtender maintains file and folder information whether the media is online or offline. This enables you to take hardware devices offline for maintenance without concerns about whether
DiskXtender will be able to find the files or media when the device is set online again. Users and applications can always see their files on an extended drive.
The following topics provide an overview of DiskXtender for Windows and instructions for configuring the system after installation:
◆ Understanding DiskXtender for Windows ... 26
◆ Starting the File System Manager Administrator... 27
◆ Understanding the Administrator interface... 29
◆ Verifying the DiskXtender version ... 31
◆ How to configure DiskXtender ... 32
Understanding DiskXtender for Windows
EMC® DiskXtender® for Windows is an automated, policy-based file system
archiving solution for long-term data retention.
DiskXtender extends primary volumes by making them seem to have an unlimited amount of space. User data is automatically migrated from the local Windows NT File System (NTFS) or Resilient File System (ReFS) volume to secondary storage based on system policies. However, the files still appear to reside on the local volume. Users and applications can seamlessly recall the data from secondary storage when necessary for viewing or editing.
For example, users on the network may typically save data to a drive on a Microsoft Windows file server. If the drive is an NTFS or ReFS volume, you can use
DiskXtender to move the files to media, such as an EMC Centera® content
addressable storage (CAS) system or tape in a library managed by DiskXtender MediaStor™, without affecting the file listing as seen by the end user.
Starting the File System Manager Administrator
The File System Manager Administrator window provides a user-friendly interface that enables you to configure the DiskXtender system.
The Administrator can run on the same server where DiskXtender is installed. It can also be installed as a Remote Administrator on a different computer, which enables you to configure one or more DiskXtender servers on the network. The DiskXtender installation guide provides details on remote administration.
To start the Administrator, open the Microsoft Windows Start menu and select
Programs > EMC DiskXtender File System Manager > DiskXtender Administrator. The DiskXtender File System Manager Administrator window appears, as
illustrated in Figure 1 on page 27.
When you open DiskXtender for the first time, the Initial Configuration Wizard helps you set up a media service, add a media folder, and set up a basic move rule and migration. This enables you to take advantage of DiskXtender immediately after you have installed it. The Initial Configuration Wizard appears the first time you start DiskXtender, and every time until you have configured a media service. You can use the wizard to set up an EMC Centera or NAS media service.
Figure 1 File System Manager Administrator window
Understanding the Administrator interface
The main portion of the File System Manager Administrator window, which is illustrated in Figure 1 on page 27, is for navigation and information display, and is split into three panes:
◆ The left pane of the window, or the tree view, contains the tree-like structure from which most commands are performed.
◆ The top right pane, or the contents view, displays the contents of the item currently selected in the tree.
◆ The bottom right pane, or the description view, displays a description or detailed properties of the item selected.
The Administrator window also contains several additional components that enable you to navigate through and configure DiskXtender:
◆ The menu bar contains the menu commands and can be found at the top of the window.
◆ The Computer drop-down list, which enables you to switch between DiskXtender servers that have been configured for remote administration, can be found just below the menu bar on the left.
◆ The toolbar, which contain toolbar icons that enable you to perform frequently used functions, can be found just below the menu bar to the right of the Computer drop-down list.
◆ The status bar, which displays information about the selected command or toolbar icon, as well as errors or warnings that occur, can be found at the bottom of the window.
Advanced mode
The Advanced mode is an option to display or hide advanced options and features available in the user interface. You can enable the Advanced mode from the Options tab of the Service Properties dialog box.
When the Advanced mode option is enabled, all the advanced features and options in DiskXtender become available to the user, depending on the media services that are configured. By default, the Advanced mode option is disabled and should be enabled only for advanced users.
Setting a timeout interval
You can specify a timeout interval for the File System Manager Administrator interface.
Understanding the timeout interval
If the DiskXtender server is busy when you issue a command through the File System Manager Administrator, DiskXtender waits for the configured timeout interval. If the server is unable to respond to the command within the timeout interval, control is returned to the Administrator so that you can continue system configuration.
If the server remains unresponsive for two or more consecutive refresh cycles, a message appears in the tree view to indicate the condition. If the server remains unresponsive for 10 consecutive refresh cycles, the Administrator interface automatically disconnects from the server.
In the event of a timeout error, you might be prompted to retry or cancel the request.
Searching in the Administrator
As you add multiple components, such as extended drives, media folders, and media, and multiple DiskXtender servers for remote administration to the system, the extended drive tree might become so large that it becomes difficult to locate a specific node of the tree. You can use the Find command in the Tree menu to quickly locate occurrences of text within the extended drives tree.
By right-clicking the media group, you can select one of these options:
◆ View All Media
◆ View Only Full Media
◆ View Only Active Media
Verifying the DiskXtender version
The About dialog box, illustrated in Figure 2 on page 31, provides details on the version of DiskXtender that is installed, including the release number, as well as any service packs, patches, or hotfixes that have been applied. Version information is provided for both the client (the Administrator interface), as well as for each DiskXtender server/service that the Administrator is managing.
Figure 2 About dialog box
To access the About dialog box, open the Help menu in the Administrator and select
How to configure DiskXtender
Configuring DiskXtender involves adding a media service, assigning an extended drive, selecting files that will be moved from the primary storage to secondary storage and setting up the migration schedule. You can use any of the following methods to configure DiskXtender:
◆ “Configuration through the Initial Configuration Wizard” on page 32
◆ “Configuration through menu options” on page 32
Configuration
through the Initial
Configuration
Wizard
When you open DiskXtender for the first time, the Initial Configuration Wizard helps you set up a media service, add a media folder, and set up a basic move rule and migration. The Initial Configuration Wizard appears the first time you start
DiskXtender, and every time until you have configured a media service. You can use the wizard to set up an EMC Centera or NAS media service.
If you have not yet set up a media service, you can access the Initial Configuration Wizard from the Service menu > Initial Setup Wizard.
Note: The Initial Configuration Wizard is disabled for DiskXtender installations on a cluster. The wizard does not pop up the first time the DiskXtender administrator window is opened on a cluster node, nor can it be accessed from the Service menu.
Configuration
through menu
options
To configure DiskXtender after installation: 1. Connect DiskXtender to a storage device:
• To use an EMC Centera cluster, provide the connection information to DiskXtender and create virtual pieces of media that simulate divisions of the EMC Centera cluster. Chapter 3, “Connecting to EMC Centera,” provides details.
• To use a share on a network-attached storage (NAS) device, create the shares, and connect DiskXtender to the shares. Each share is considered an individual piece of media in DiskXtender. Chapter 4, “Connecting to Network-Attached Storage,” provides details.
• To use a storage device with removable media such as tape or optical, connect DiskXtender to the software that manages the device (either EMC
DiskXtender MediaStor or StorageTek ACSLS) and add media to the device.
Chapter 5, “Connecting to Optical and Tape Devices,” provides details. • To use an IBM Tivoli Storage Manager (TSM) system to store DiskXtender
files, install the TSM client on the DiskXtender server, connect DiskXtender to the TSM server, and then create virtual pieces of media that simulate divisions of the TSM server. Chapter 6, “Connecting to Tivoli Storage Manager,”
provides details.
• To use the cloud media to move files using DiskXtender, configure the cloud media (EMC Atmos) as a media service and create virtual cloud media.
Chapter 7, “Connecting to Cloud Storage,” provides details.
3. Identify or create the folders on the extended drive that will contain the files to move to storage. These folders are called media folders in DiskXtender. A media folder can be a subfolder on the extended drive, or you can manage all the files on the extended drive by specifying the root of the drive as a media folder.
“Extended drive directory structure” on page 65 provides details on planning for and creating media folders.
4. Configure file migration. In DiskXtender, the migration of a file is actually a copy. When DiskXtender moves a file to storage, it is really copying the file data to media and adding extended attribute information to the file on the drive. The file is then managed by DiskXtender, and the data resides both on the extended drive and on the media.
To enable file migration, specify the criteria that files must meet before
DiskXtender migrates them. You also must specify the media to which the files should be moved. Details on the available options for file migration are provided in Chapter 9, “File Migration.”
5. Configure file purging. When DiskXtender purges a file, it removes the file data from the extended drive and leaves behind a file tag on the extended drive. Purging files frees space on the extended drive, while maintaining the appearance that the files are still on the drive. A purged file is still accessible, and to a user machine, appears to reside on the extended drive.
You can choose to automatically purge files from the extended drive either: • Immediately after they are moved to storage
• When extended drive space is low
• Each night during the next background scan
Chapter 12, “Purging Files,” explains how to develop an appropriate purging strategy and enable purging.
6. (Optional) If you are planning to index and search for files on the extended drive by using the DiskXtender Search Module, then configure file indexing.
Guidelines for developing an indexing strategy and instructions for enabling indexing are available in Chapter 11, “Indexing Files.”
7. (Optional) Enable the DiskXtender Recycler to protect against the accidental deletion of files from the extended drive. If the DiskXtender Recycler is enabled and a user accidentally deletes a file, you can restore the file to the extended drive. The DiskXtender Recycler functions similarly to the Microsoft Windows Recycle Bin, but only affects files on a drive extended by DiskXtender.
“Recovering files from the DiskXtender Recycler” on page 124 provides details on the Recycler.
Note: The Recycler resides on the extended drive. As a result, the disk space used by the Recycler factors into the total available disk space for the extended drive. If you enable the Recycler, set a schedule for emptying the Recycler on a regular basis to help maintain an adequate amount of space on the extended drive.
8. (Optional) Configure automatic deletion of files. DiskXtender can automatically delete files from the extended drive based on certain file criteria by using delete rules.
If you are protecting files with retention for a period of time, you may want to automatically delete the files when the retention expires and the files are no longer needed.
“Automatically deleting files” on page 120 provides instructions on creating delete rules.
9. Develop a comprehensive backup and recovery strategy for the DiskXtender system. Chapter 16, “Backup and Recovery,” provides guidance on the aspects of the DiskXtender system that must be protected, as well as best practices for the tools needed for backup and recovery.
Licensing
DiskXtender licensing is capacity-based. A capacity-based license specifies the number of DiskXtender servers allowed, as well as the quantity of extended drive data that DiskXtender can manage. If you are installing DiskXtender in a Microsoft clustering environment or AutoStart domain, the license must account for each active File System Manager installation, and it must also be cluster-enabled. Additional licensing details are available in the DiskXtender installation guide.
License Server
DiskXtender licenses are managed by the Xtender Solutions License Server product. The computer on which you install License Server depends on the environment:
◆ If License Server must manage only a DiskXtender license for a single
DiskXtender installation, then it can be safely installed on the DiskXtender server without a significant impact on performance.
◆ If License Server must manage a DiskXtender license for multiple DiskXtender installations, then you may want to install it on a separate computer that is accessible to all of the DiskXtender servers.
◆ If License Server must manage licenses for both DiskXtender and multiple ApplicationXtender® clients, then it should be installed on a separate computer to
avoid an impact on DiskXtender server performance.
The computer on which you install License Server determines the release of License Server that you need:
◆ If you plan to install License Server on a DiskXtender 6.5 SP 7 server, then use License Server 6.5 SP 7.
◆ If you plan to install License Server on a separate machine from DiskXtender, then the operating system on the machine determines the necessary License Server release.
• For a 32-bit operating system, use a 32-bit release of the License Server. • For a 64-bit operating system, use a 64-bit release of the License Server.
Table 2 on page 35 provides details on supported environments. Table 1 Supported DiskXtender environments for License Server
License Server release Supported DiskXtender environments
6.3 (32-bit) • One or more DiskXtender 6.3 (32-bit) servers • One or more DiskXtender 6.4 (64-bit) servers
• A mix of DiskXtender 6.3 and DiskXtender 6.4 servers in the same environment 6.4 (64-bit) • One or more DiskXtender 6.3 (32-bit) servers
• One or more DiskXtender 6.4 (64-bit) servers
• A mix of DiskXtender 6.3 and DiskXtender 6.4 servers in the same environment 6.5 SP7 • One or more DiskXtender 6.5 SP7 servers
License Server 6.5 SP7 supports the following 32-bit operating systems:
◆ Microsoft Windows Server 2003 Standard, Enterprise, or Small Business Edition with SP2
◆ Microsoft Windows Storage Server 2003 Standard or Enterprise Edition SP2 R2
◆ Microsoft Windows Server 2008 Standard, Enterprise, or Small Business Edition SP2
License Server 6.5 SP7 supports the following 64-bit operating systems:
◆ Microsoft Windows 2003 Standard or Enterprise Edition with SP2
◆ Microsoft Windows Server 2008 Standard or Enterprise Edition with SP2 and SP1 R2
◆ Microsoft Windows 2012 Server
◆ Microsoft Windows 2012 Storage Server R2
The minimum system requirements for these operating systems are sufficient to run License Server.
The License Server computer must belong to the same domain as all other DiskXtender servers.
Before you install License Server, create a service account for License Server. The account should have access to the network and be a local administrator on the License Server computer.
The necessary files to install License Server are available on the DiskXtender installation CD. A wizard leads you through the steps to install License Server.
Evaluation licensing
When you install File System Manager, you are prompted to select whether you are installing a licensed version or a 30-day evaluation version. If you choose a 30-day evaluation license, you must set up a license and point the program to the License Server before the 30 days expire, or the functionality of the product is disabled.
Adding a license
To obtain a product license and add the license for DiskXtender to use:1. Determine the machine ID number for the License Server computer by opening the General tab of the Service Properties dialog box in the License Server
Administrator after you install License Server. The machine ID is required to generate a product license.
2. Use the License Management process available on EMC Online Support, or contact the EMC Licensing Support team at [email protected].
If you receive DiskXtender product license information in the form of a file with a .lic extension, you have a license file. If you receive DiskXtender product license information in the form of a series of numbers and letters, you have a license key. 3. Use the New License Wizard in the License Server Administrator to add the
license file or key to License Server.
To start the New License Wizard, open the Tools menu in the License Server
4. Connect DiskXtender to License Server:
a. If License Server is installed on a different computer than DiskXtender, give the necessary user accounts the required privileges on the License Server computer:
– Add the DiskXtender service account to the local Administrators group on the License Server computer.
– If you log in to the DiskXtender server by using an account other than the DiskXtender service account, add the account to the local Administrators group on the License Server computer.
b. Use the Edit product license information option on the DiskXtender setup wizard to point DiskXtender to the License Server installation with the license.
Licensing in a cluster
When you obtain a license for a DiskXtender installation in a cluster, ensure that the license is cluster-enabled and that the license accounts for each active DiskXtender installation in the cluster.
In addition, decide whether to manage the DiskXtender license from within the cluster or on a server outside the cluster.
When installed in the cluster, License Server runs actively on one node in the cluster. It can then fail over to one of the other nodes in the environment. In other words, License Server runs in active/passive mode in a cluster.
You can assign the License Server cluster resources to the same virtual server group as the DiskXtender resources. This enables License Server to fail over to another node in the cluster at the same time as DiskXtender. Alternatively, you can create a separate virtual server for the License Server cluster resources. This virtual server could fail over separately from DiskXtender, if necessary, or it could fail over at the same time, if the node with both virtual servers fails.
You can migrate files on a DiskXtender extended drive to an EMC Centera cluster. The following topics provide details on configuring and managing the environment:
◆ How DiskXtender works with EMC Centera ... 40
◆ Prerequisite steps to connect to EMC Centera ... 58
◆ Managing the lifecycle of EMC Centera media ... 65
◆ Expectations for files migrated to EMC Centera ... 68
◆ Adding custom metadata to files on EMC Centera ... 70
How DiskXtender works with EMC Centera
The following topics provide details on how DiskXtender communicates with EMC Centera, as well as how various features in the two products complement each other:
◆ “Connecting DiskXtender and EMC Centera” on page 40
◆ “Virtual EMC Centera media” on page 42
◆ “Content addressable storage” on page 43
◆ “Renaming EMC Centera folder” on page 44
◆ “EMC Centera storage strategies” on page 46
◆ “Communication threads” on page 49
◆ “Compliance through retention and audit” on page 54
◆ “Replication” on page 56
Connecting DiskXtender and EMC Centera
When you install or upgrade DiskXtender, the EMC Centera Software Development Kit (SDK) is installed automatically on the DiskXtender server to enable
communication between DiskXtender and an EMC Centera cluster.
When you create an EMC Centera media service in DiskXtender, you specify the connection string that the EMC Centera SDK uses to enable DiskXtender to connect to an EMC Centera cluster. The connection string for the primary EMC Centera includes information about the EMC Centera access nodes of primary EMC Centera, as well as the access profile that should be used for the DiskXtender connection. The connection string for the replica EMC Centera includes information about the EMC Centera access nodes of replica EMC Centera, as well as the access profile that should be used for the DiskXtender connection.
DiskXtender connects with the access nodes by using a TCP/IP connection.
Access nodes Each EMC Centera cluster contains two or more nodes with the access role. You should specify as many access nodes on the cluster in the connection string as possible.
When the EMC Centera SDK attempts to open a connection to the cluster for DiskXtender, it attempts to connect to the first access node listed in the connection string. If the connection to the first access node is successful, the SDK queries for and internally stores information about all available access nodes in the cluster.
Communication between EMC Centera and DiskXtender is then automatically load-balanced across this set of nodes.
If the connection to the first access node fails, however, then the SDK attempts to connect to the second access node listed in the connection string. If the connection to the second access node fails, then the SDK attempts to connect to the third access node listed in the connection string, and so on. This process continues until the SDK is able to successfully connect to an access node. Once the connection is made, information about all available access nodes is stored by the SDK, regardless of the number of access nodes listed in the connection string.
In addition, you cannot edit access node information in DiskXtender after you create the media service. As a result, you cannot add or remove node information for an existing media service.
Because you cannot edit access node information in DiskXtender, equate each access node IP address with a node name alias before you create the media service. To configure node name aliases, either add the appropriate entries to a common DNS server or edit the local HOSTS file on the DiskXtender server.
The connection string for a media service is limited to 512 characters. Keep this limit in mind when defining node name aliases. The aliases should be kept to a reasonable length. Otherwise, you may not be able to specify a sufficient number of access nodes on the connection string to enable reliable connections in the event of a node failure. You can then specify the aliases instead of the IP addresses when you create the media service. If you later need to change the access node IP addresses, you only need to change the HOSTS file or DNS entries. You might need to change the access node IP addresses if it becomes necessary to replace an access node.
Note: If you add an access node to the EMC Centera cluster after you create the media service, you cannot add the address information to the media service connection string. However, DiskXtender can connect to the access node. This is because the EMC Centera SDK internally discovers and stores information about all available nodes after a successful connection is made to one of the current access nodes in the connection string.
If you use EMC Centera replication, do not specify connection information for the access nodes of the target clusters. “Replication failover” on page 56 provides additional details.
Pools and profiles EMC Centera security is based on pools and application profiles:
◆ An application pool, or virtual pool, is a logical area on an EMC Centera device where applications can store their data. Virtual pools enable you to logically separate data on an EMC Centera device. This is particularly useful if there are multiple applications with different security needs writing data to an
EMC Centera device.
◆ Access profiles provide access to one or more EMC Centera pools. Pools grant capabilities to applications that are accessing EMC Centera by using the profile. For DiskXtender, the profile must have the Write, Read, Delete, and Query capabilities. To allow privileged deletes of retained files, the profile should also have the Privileged Delete capability.
◆ A .pea file, generated while creating or updating an access profile, is a clear text, XML-formatted, nonencrypted file that can be used by system administrators to communicate and distribute authentication credentials to application
administrators.
Each EMC Centera cluster can have multiple virtual pools and multiple access profiles.
The EMC Centera online help provides information on pools, access profiles, and .pea files, which should be configured by an EMC Centera technical representative. When you create an EMC Centera media service in DiskXtender, specify a .pea file when you create the media service. You cannot edit a media service later to add a .pea file.
and access profiles on the two clusters are merged. This merged .pea file, which enables access to both pools with a single profile, should be configured by an EMC Centera technical representative.
If you have multiple, separate pools and access profiles—each pair with its own corresponding .pea file—then you can create multiple EMC Centera media services. Multiple media services enable you to further separate data you are writing through DiskXtender.
If you do not specify a .pea file when you create an EMC Centera media service, then DiskXtender uses the Anonymous profile to connect to EMC Centera.
Note: The Anonymous profile is disabled in EMC CenteraStar® 3.1 and later. If CenteraStar 3.1
or later is installed on the EMC Centera cluster, you must use an access profile when you create a media service in DiskXtender. If you use an earlier release of CenteraStar with DiskXtender and you upgrade to 3.1 or later, you can continue to use the Anonymous profile.
Virtual EMC Centera media
EMC Centera media is virtual, meaning that a piece of media defined in DiskXtender does not specifically correspond to a physical piece of media (like a tape cartridge). Instead, the virtual media is designed to simulate divisions of an EMC Centera cluster.
DiskXtender provides support for EMC Centera Virtual Access. You can use EMC Centera Virtual Access nodes with DiskXtender just like any other EMC Centera nodes. It is transparent to DiskXtender and all EMC Centera features continue to work same as before.
The use of virtual media enables you to take advantage of the flexible file migration features available in DiskXtender.
Each piece of virtual media can contain as much as 256 GB of file data and metadata, or can store up to 100,000 files. This is an either/or limit. It is possible that you can fill a piece of EMC Centera media with 100,000 files but remain well under the 256 GB size limit.
When you create a piece of virtual media, the 256 GB of space is not reserved on the EMC Centera device. Space is used on the EMC Centera device only when a file is migrated from DiskXtender.
Note: Because space is not reserved on the EMC Centera device for virtual media, if you meet the limit of 100,000 files before you meet the limit of 256 GB, the size of the piece of media is limited to the size required for the 100,000 files. In other words, the difference between the total size of the 100,000 files and 256 GB is not wasted space on the EMC Centera device.
The size limit for EMC Centera media is imposed so that finding a file associated with a piece of media does not take an inordinate amount of time. When either threshold is reached, the media is considered full and cannot receive any more files, although files can be retrieved from the media when necessary. Full media appears with a blue label in the File System Manager Administrator.
You can create as many pieces of virtual media as necessary. You are limited only by the total amount of space available on the EMC Centera device.
When a piece of virtual media is created in DiskXtender, a corresponding EMC C-Clip™ for the media is created on the EMC Centera device. Once the C-Clip is
created, the content address (CA) of the C-Clip is sent back to DiskXtender and is stored in the Microsoft Windows registry on the DiskXtender server.
When DiskXtender migrates a file to a piece of EMC Centera media, a C-Clip for the file is created on the EMC Centera device. Metadata about the piece of virtual media associated with the file is stored with the file on the EMC Centera device.
In addition, DiskXtender creates a special C-Clip on the EMC Centera cluster daily at midnight (EMC Centera cluster time). This new C-Clip contains a list of all media C-Clips and folder rename C-Clips associated with those media currently on the system. One C-Clip is created for each EMC Centera media service. The CA for the C-Clip is stored in the DiskXtender event log when the C-Clip is created. If a disaster occurs, an EMC Customer Support Representative can retrieve the C-Clip to develop a list of media to restore to DiskXtender.
There are two ways to create virtual EMC Centera media through DiskXtender:
◆ Automatically through the media group, either when free space in the media group falls below a certain number of megabytes or when the number of available pieces of media falls below a certain level.
◆ Manually through the media service. Use this method to create individual pieces of media. Then allocate the media to the extended drive and add it to a media group to make it available for file migration. This option is not recommended for most environments.
To avoid confusion and simplify media naming conventions, use only one media creation method.
If you no longer need the files that have been written to a piece of EMC Centera virtual media, you can run a Format media task on the media to clear the files from the EMC Centera device. The EMC Centera Garbage Collection feature then reclaims the space made available by the deleted files.
Note: The Format task may take a significant amount of time to complete for EMC Centera media.
Content addressable storage
With content addressable storage (CAS), EMC Centera ensures that applications, such as DiskXtender, no longer have to track the physical location of stored information. Instead, with the CenteraStar software operating environment, EMC Centera creates a unique identifier, based on the attributes of the content, that applications use for retrieval.
The unique identifier is called a content address (CA). The CA uniquely represents the object and its associated metadata, and is required to retrieve the object.
The following topics provide details on how DiskXtender writes files to EMC Centera media, as well as how to customize file migration between DiskXtender and EMC Centera.
How DiskXtender writes files to EMC Centera
Note: You can also add custom metadata to CDFs by using DiskXtender media groups. This custom metadata can be used to enhance EMC Centera Seek and Chargeback Reporter reports. “Adding custom metadata to files on EMC Centera” on page 70 provides details.
Another CA for the CDF is generated, and then DiskXtender stores the CDF and the file data in a package on the EMC Centera cluster. This complete package, which contains both file data and metadata, is called a C-Clip and is illustrated in Figure 3 on page 44.
Figure 1 EMC Centera C-Clip for a DiskXtender file
The CA for the CDF is returned to DiskXtender and stored for the file. When the file is purged from the extended drive, this information can be used to retrieve the file data from EMC Centera.
Renaming EMC Centera folder
You can rename EMC Centera folder through the Microsoft Windows Explorer. The following topics provide details.
What happens when you rename an EMC Centera folder
Renaming an EMC Centera folder on the extended drive changes the folder name on the EMC Centera media. DiskXtender allows you to rename the folder and the subfolders on an EMC Centera media. Renaming of folders can be done any number of times. When you rename a folder, the transactions are logged to the folder rename master clip of each EMC Centera media associated with folder rename.
When a media task such as compact, purge, fetch, prefetch, restore, or report is performed, the DiskXtender processes the folder rename transactions to restore files to the latest EMC Centera folder in the media.
Note: Performance of EMC Centera media tasks may be affected as each of the media tasks involve processing the folder rename transactions log and restoring files to the latest folder.
GEN-000914 C-Clip
CDF (XML file)
• CA for file
• Metadata (filename, creation data, and so on)
CA for CDF
3C08JM40C8AMMe0N8ATEJHC2DQN
When the EMC Centera media is offline, you can continue to rename the folders in the extended drive. However, the synchronization of folder names on the EMC Centera will take place when the media is online. Because of the synchronization, there might be a delay in performing the media tasks as well as file fetching operations.
Renaming EMC Centera folder uses the EMC Centera and DiskXtender time for logging the transaction and any change to the EMC Centera time or the DiskXtender server time may result in files retrieved to a different folder when a media task is performed.
IMPORTANT
Any system errors while processing folder rename transactions result in using the original EMC Centera folders.
Note: While renaming a folder, if the recycler is enabled, and you delete or move the file under this folder to recycle bin. When you try to restore the same file, the file is restored to the original folder.
How to enable EMC Centera folder rename
To enable EMC Centera folder rename:
1. Right-click the extended drive in the DiskXtender Administration window. 2. Select Extended Drive Properties.
Extended Drive Properties dialog box appears. 3. Select Options page.
4. Scroll down and select Centera folder rename option. 5. Select the Allow Centera folder rename radio button. 6. Click OK.
IMPORTANT
You must be a local administrator on the DiskXtender server to enable EMC Centera folder rename.
To enable EMC Centera folder rename after an upgrade
To be able to use the EMC Centera folder rename feature after upgrading to the latest release of DiskXtender, perform these additional post-upgrade steps:
1. Run the DxDmChk utility on the extended drive on which to enable folder renames.
2. In case of a cluster environment, run the DxDmChk/X option on all active cluster nodes.
IMPORTANT
!
How to rename a EMC Centera folder
To rename EMC Centera folder using Windows Explorer:
1. Open the Microsoft Windows Explorer and navigate to the EMC Centera folder on the extended drive.
2. Right-click the folder and select Rename.
The folder name appears highlighted in the tree view. 3. Type a new name for the folder, and then press Enter.
To rename EMC Centera folder using command-line interface, open the
command-line interface and change path to the EMC Centera folder on the extended drive. Use the following command to rename the folder:
c:\CenteraFolder> ren cenfolder1 cenfolder2 or
c:\CenteraFolder> rename cenfolder1 cenfolder2
When the EMC Centera media is full and you rename an EMC Centera folder, the rename transaction is successful on the extended drive as well as on the EMC Centera media.
Note: When multiple rename transactions are done on the extended drive and the user tries to fetch a file, there will be a delay in accessing the file. This is because, logging all rename transactions to the EMC Centera must be complete before fetching a file from the media. However you can change this behavior in the Extended drive option.
When you rename a folder from a remote client that is being accessed in the local server, the folder rename transaction fails. Similarly, when you rename a folder from a local server that is being accessed from a remote client, the folder rename
transaction fails.
EMC Centera storage strategies
Data can be stored on an EMC Centera device by using one of two storage strategies:
◆ Storage Strategy Capacity is designed to maximize the storage capacity of the cluster by taking advantage of single-instance storage. With single-instance storage, duplicate copies of a file are not stored on the cluster. Only a single copy of a file is stored.
Note: DiskXtender also works with both EMC Centera data protection mechanisms; Content Protection Mirrored (CPM) and Content Protection Parity (CPP). The EMC Centera protection mechanism (CPM or CPP) is transparent to DiskXtender.
DiskXtender options to tune CAS
DiskXtender provides media service options that enable you to customize the way files are stored to EMC Centera, and therefore maximize performance:
◆ Collision avoidance — Collision avoidance ensures that a unique CA is created for each file stored on EMC Centera, even if the file is a duplicate of another file stored on the cluster. If the file is edited and re-migrated, then a different unique CA is created.
This feature is designed to prevent the unlikely event where the same CA is created for different files. If the files are purged and you attempt to fetch the second file, the data for the first file with the CA is returned instead, and the data for the second file is irretrievable.
Collision avoidance should not be used in most environments because it prevents the primary benefit of single-instance storage—the elimination of duplicate content so that only a single copy of each file is stored. It should be used only in environments where even the most remote possibility of data loss is
unacceptable, or in environments where single-instance storage is forbidden, usually due to legal regulations.
Note: If you enable collision avoidance, each file is stored uniquely, even if you use Storage Strategy Capacity (single-instance storage).
◆ Embedded BLOBs — You can set a threshold for embedding small BLOBs (file data) in the CDF. Embedding file data in the CDF can decrease read and write times, since the overhead required to manage two objects (CDF and BLOB) is greater than the overhead required to manage a single object.
Figure 4 on page 47 illustrates an embedded BLOB, while Figure 5 on page 48
illustrates a separate CDF and BLOB.
Figure 2 Embedded BLOB for a file stored on EMC Centera
Figure 3 Separate CDF and BLOB for a file stored on EMC Centera
To maximize the performance benefits of this feature, files smaller than 100 KB (the maximum value for the option) should be embedded in the CDF.
If the EMC Centera is configured for Storage Strategy Capacity (single-instance storage), embedding BLOBs for files smaller than 100 KB will not allow you to realize the benefits of the storage strategy for these files. This is because the file content is embedded in the CDF. If you embed the BLOBs for files smaller than 100 KB, then single-instance storage is applied only to files larger than 100 KB. Note: The total file size (all streams and the stream tags) must be less than the embedded BLOB threshold before the BLOB is embedded in the CDF.
◆ Client-side ID calculation — The Client-side ID (hash) calculation option enables you to control whether the EMC Centera API calculates the CA for a piece of data before the data is sent to the EMC Centera cluster. If the calculation results in the determination that the data already exists on the cluster, the data is not sent. Client-side ID calculation can improve performance and maximize storage efficiency under the following conditions:
• Files are larger than 10 MB in size.
• Identical data is likely to be sent to EMC Centera.
• You use Storage Strategy Capacity (single-instance storage).
Client-side ID calculation is not beneficial under the following conditions:
• File data is embedded in the CDF (in other words, when you set an embedded BLOB threshold of greater than zero).
• Files are small (less than 10 MB).
• You use Storage Strategy Performance or collision avoidance and files are stored uniquely even if they are identical.
Note: If you use CenteraStar 3.0.2 or later, or 3.1.1 or later, additional configuration steps are required on the EMC Centera device to enable client-side ID calculation. Contact an EMC Centera technical representative for assistance in enabling this feature if you use one of the specified CenteraStar versions.
Garbage Collection When a file is deleted from the extended drive, a delete transaction is issued and flushed to the target storage device. Delete transactions can flush every minute, depending on what other transactions have been initiated.
When EMC Centera receives a delete transaction from DiskXtender, the CDF is deleted from the EMC Centera device, and the BLOB is left there (orphaned). CDFs not under retention can be deleted from any type of EMC Centera device.
If the EMC Centera Garbage Collection process is enabled, then the BLOBs with deleted CDFs are removed from the EMC Centera device and space is recovered. The file data for deleted files is removed from the EMC Centera device and is not
recoverable. If Garbage Collection is disabled, however, then the BLOBs with deleted CDFs remain on the EMC Centera device and occupy space.
Garbage Collection and the DiskXtender Recycler
If the DiskXtender Recycler is enabled, files are placed in the Recycler when they are deleted from the extended drive. A delete transaction is sent to the EMC Centera cluster when the file is deleted from the Recycler.
When a significant number of delete transactions are sent to the EMC Centera cluster, the completion of those transactions may take a long time. During that time, file fetches may be delayed or even canceled due to timeout issues. Do not empty the Recycler when users are most likely to access the system. Or, if the Recycler is disabled, do not delete a significant number of files from the extended drive when users are most likely to access the system.
Communication threads
Each access node of an EMC Centera has a certain number of available
communication threads. The optimum performance level is reached when each EMC Centera access node processes approximately 20 simultaneous connections. You can exceed 20 connections for each access node. However, performance degradation typically results.
When an application communicates with an EMC Centera cluster, it uses one or more of these threads to pass data to and from the EMC Centera cluster. With DiskXtender, these threads are used to read data from and write data to the EMC Centera cluster. It is important to understand the communication process between DiskXtender and EMC Centera so that you do not exceed the maximum number of available
communication threads. The following topics provide additional details and guidance on configuring options that enable you to control the lines of communication and maximize performance.
How DiskXtender uses the communication threads
By default, DiskXtender can either read data from or write data to each piece of virtual media during any given time period. In other words, if DiskXtender is writing File G to a piece of media and a user requests File A from that same piece of media, then the user must wait until File G is written before File A is retrieved and
Figure 4 Single thread per piece of virtual media
In an active environment where file migration is necessary at the same time that file fetches are likely to occur, you can configure DiskXtender to both read from and write to a single piece of media at the same time. This functionality is available through the
Enable simultaneous moves and fetches feature, which appears on the Options tab of the Service Properties dialog box. When simultaneous moves and fetches are enabled, two EMC Centera threads may be occupied by DiskXtender communication with a single piece of media—one for moves and one for fetches, as illustrated in
Figure 7 on page 51.
GEN-000583
Step 2: After File G is migrated, then File A, which resides on Virtual Media 1, can be fetched Step 1: File G is migrated to Virtual Media 1 on the EMC Centera cluster
Virtual Media 1 Virtual Media 2 Virtual Media 1 Virtual Media 2 File G Extended drive File A Extended drive
EMC Centera cluster
Figure 5 Simultaneous moves and fetches
With simultaneous moves and fetches enabled, DiskXtender will use only two threads for a piece of media if it is both moving and fetching files. It will not open two threads to a piece of media for moving files, nor will it open two threads for fetching files.
If there are multiple pieces of virtual media in a media group—and even multiple media groups with multiple pieces of media in each—then a single DiskXtender installation can occupy numerous communication threads with an EMC Centera cluster at any one time. DiskXtender can initiate and maintain as many as 256 simultaneous connections to EMC Centera, regardless of the number of configured EMC Centera media services.
DiskXtender will not reserve a thread to a piece of media if it does not need to. Communication threads to EMC Centera are initiated and maintained only if a file is requested from media or if there are files that need to be migrated and the file migration schedule is active.
GEN-000585
Virtual Media 1
Virtual Media 2
Virtual Media 3
Virtual Media 4
EMC Centera cluster File A
File G
File G is migrated to Virtual Media 1 at the same time that File A is fetched from Virtual Media 1
DiskXtender writes files randomly to any piece of active media in a media group. This enables DiskXtender to continue writing files to media at the same time that it is fulfilling fetch requests for files on other pieces of media, as illustrated in Figure 8 on page 52.
Figure 6 Random migration to EMC Centera
You can configure DiskXtender to write files to media sequentially rather than randomly by using the Media fill method feature on the Options tab for each media group. However, sequential fill is strongly discouraged for EMC Centera media groups because it can lead to poor performance. “Media group considerations for
EMC Centera” on page 71 provides additional information.
Calculating the optimal number of available threads
The equation for determining the optimal number of threads available for DiskXtender file migration and file fetches is as follows:
(N x 20) - A - R = Available threads where:
◆ N is the number of access nodes in the EMC Centera cluster. ◆ 20 is the optimal number of threads per node.
◆ A is the number of threads used by other applications, including other DiskXtender installations.
◆ R is the number of threads used for EMC Centera replication, if replication is enabled. GEN-000586 Virtual Media 2 Virtual Media 3 Virtual Media 4 Media group 2 Virtual Media 5 Virtual Media 6 Virtual Media 7 Virtual Media 8 File E File F File G File H File D File C File B File A Media folder Communication threads Extended drive Media group 1
EMC Centera cluster
