Executive summary ... 2
What is a Virtual Tape Library? ... 2
Comparing the VTL and a standard tape library ... 3
Will different virtual and physical drive types cause problems or affect performance? ... 3
Advanced Backup to Disk technology using a Data Protector File Library ... 4
Overview—Advanced Backup to Disk ... 4
Backup to disk-based devices—benefits ... 5
HP Data Protector Software offers three different device types ... 6
What is a file library? ... 6
Distributed file media format (DFMF) file library ... 8
Enhanced incremental backup (Incremental forever) ... 9
How does enhanced incremental work in Data Protector? ... 10
Incremental forever paradigm ... 10
Object consolidation ... 11
Space-efficient synthetic full backup (virtual full) ... 12
VLS Automigration option ... 13
VLS Automigration data copy methods ... 13
How to integrate and configure Automigration in Data Protector ... 13
How is the Automigration initiated by Data Protector ... 16
VLS Automigration advantages ... 17
Limitations ... 17
VLS versus Data Protector file libraries ... 18
Data Protector GUI wizard ... 19
Automatic and intelligent space management ... 19
Improved disk full handling ... 19
Use case—Disk staging ... 20
New file library license: B7038** ... 21
Advanced Backup to Disk Licensing (B7038AA/BA/CA) ... 21
HP Data Protector Software licensing using a VTL library ... 21
Summary and conclusions ... 22
For more information ... 23
HP Data Protector Software Advanced Backup
to Disk Integration with Virtual Tape Libraries
This white paper provides a better understanding of the integration of HP Data Protector Software with Virtual Tape Libraries by utilizing the Advanced Backup to Disk functionality available with the HP Data Protector Software. After reading this paper, you should be able to determine the difference between a Data Protector file library device and a Virtual Library. You should also be able to
determine how to employ the licensing structure of HP Data Protector Software to best suit your customer’s needs.
What is a Virtual Tape Library?
A Virtual Tape Library (VTL) is a dedicated computing appliance that emulates the drives of a physical tape library and stores backup images to disk. Backup applications, like HP Data Protector Software, use the VTL emulated tape and library devices for backups when in fact it is an array-based
Figure 1. HP StorageWorks 6000 Virtual Library System (VLS6000)
The VTL consists of three components: computer hardware, application software, and a RAID-based array of disk drives. The application software emulates a tape library and tape drives and the RAID-based array of drives ensures no backup data is lost if a hard drive fails. These components are frequently bundled by a single vendor into an appliance.
The VTL allows a customer to configure virtual tape drives and virtual tape cartridges, and to specify cartridge capacity. The maximum number of supported virtual tape drives varies by vendor, ranging from single digits to an unlimited number of drives. And, unlike physical tape libraries, which require that additional tape drives be purchased and installed, virtual tape drives can be added to the VTL by changing the software configuration, with no additional hardware costs.
Because the VTL emulates a tape library and its drives, it does not require a change to the backup paradigm. When using Data Protector Software, you would configure the device just as you would configure any other direct/LAN/SAN–attached tape library and drive.
Comparing the VTL and a standard tape library
Problems with physical tape drives, robotic failures, and media lead to the failure of several backup jobs. These problems can be difficult to diagnose. Write errors, reported by an operating system, do not indicate whether the media or drive is at fault. The administrator must then spend time determining whether the media or drive caused the problem. In addition, restoring from physical tape can involve multiple tape cartridges. If one of these cartridges fails, the restore most likely will be incomplete or fail altogether.
Because all VTLs use RAID storage, read and write failures are extremely unlikely, so the VTL effectively eliminates drive and media issues from the backup and recovery process.
Base VTL throughput can also be improved by adding more capacity (disk drives), controllers, and Fibre Channel (FC) ports. However, with newer tape drives capable of backing up data, with compression, at greater than 50 MB/s, backing up large amounts of multi-streamed data to physical tape may still be faster than the VTL.
Performing restores from the VTL can also be faster than using physical tape. This is likely to be the case when recovering specific files, due to the random access of disk as compared to the sequential access of tape. However, if huge amounts of data are being restored, and multiple tape drives are reading data in parallel, physical tape may be faster than the VTL.
Multiplexing or interleaving of client backup jobs to a single tape drive is often used to keep a tape drive streaming. But, if the tape drive cannot continue streaming, it either has to stop, reposition the tape, and start writing again—which has a huge impact on performance and reliability—or the drive has to slow down and write data at reduced speed. Either way, backup performance is
compromised. Multiplexing also impacts restore performance. Restoring data from a multiplexed backup takes longer because one client’s data is interleaved with many others and spread over a larger area on the tape cartridge. A VTL uses disk and provides random access to data. Rather than multiplex backups, each client can be allocated a separate virtual drive. If the disk backup is then copied to physical tape, it will not be multiplexed. Restoring from this tape will be faster than restoring from a multiplexed backup.
With no penalty imposed when configuring additional VTL drives by using Data Protector’s capacity-based licensing model—assuming the maximum allowable number of drives has not been reached— virtual drives can be allocated specifically for restore operations. This ensures that restores will be initiated quickly. Overall speed of the restore operation will still depend on available bandwidth and the size of the restore.
In most instances the VTL will be deployed as a front-end to a traditional physical tape library. Backup data can be object copied from the VTL to physical tape using the copy functions of Data Protector or using the new VLS Automigration Integration.
Will different virtual and physical drive types cause
problems or affect performance?
In the world of physical tape, drive types are chosen based on a combination of performance, media capacity, and reliability, and each has a bearing on price. These characteristics do not translate to the VTL.
There are three factors to physical tape drive performance: mount time, load time, and tape streaming speed. From the perspective of data throughput, the VTL does not simulate the performance of the
With regard to capacity, the virtual cartridges in the VTL can be configured to whatever size is desired. Although a physical DLT7000 drive uses a cartridge holding 35 GB of uncompressed data, a virtual DLT7000 cartridge can be configured to store 300 GB, 1 TB, or whatever capacity is appropriate to the application. Virtual cartridges should not be configured so large that they limit the number of concurrently running backup jobs—a VTL with 20 TB of storage can only support 20 concurrently running backup jobs if virtual cartridges are sized at 1 TB. If backup jobs are being multiplexed, very large virtual cartridges can be configured. However, the ability to avoid multiplexing is considered by many to be a significant benefit of using a VTL.
Advanced Backup to Disk technology using a Data
Protector File Library
Advanced Backup to Disk is a new functionality option for customers running HP Data Protector Software Version 5.5 and higher. Advanced Backup to Disk functionality in Data Protector improves the backup process with continuous backup of transaction log files, backup of slow clients without multiplexing, easy resource access and sharing, plus backup in tapeless branch offices, while offering fast and easy configuration and licensing. Furthermore, it allows tape virtualization with easy backup resource sharing. This new feature complements the Data Protector backup to disk technologies of Zero Downtime Backup (ZDB), Instant Recovery (IR), and the VTL. Advanced Backup to Disk allows your customer to meet the demand for fast and direct restore from disk with transparent access to data migrated to tape. This offers the ideal solution for customers who want to stage the backup on fast central disk space before moving it to tape.
Advanced Backup to Disk is enabled through the introduction of a new device type called a File Library. This feature allows the HP Data Protector Software customer to create a Data Protector file library device as a backup and recovery point.
The file library device controls the space management of the library automatically. It can be configured to automatically create or extend space on your disk device to accommodate your backup. It uses automatic retention management to allow for automatic space re-use within your file library. The file library can restore and back up in parallel and the technology is disk array
independent so you can deploy it with a multitude of different storage devices from a single disk, low-cost JBOD, to the higher end storage arrays.
The file library device is configured and used through the Data Protector GUI. The device is conceptually similar to a tape stack in that it consists of one or more files in container directories, which are the equivalent of slots in a tape stack where data is stored. In the case of the file library device, the data is stored in a series of files called file depots, which are created each time a backup to the device is made.
The file library device is supported on HP-UX, Microsoft® Windows®, Solaris, Linux, AIX, Netware, Tru64, and OpenVMS systems.
Overview—Advanced Backup to Disk
Customers have requirements for increasingly larger, faster methods of backing up and restoring data. In addition, it has become more important that the time required for data backup and restore should be reduced to a minimum so as not to impact/interrupt the day-to-day running of company applications.
This may be achieved using split mirror/snapshot technologies in ZDB configurations to create a replica of the data or through usage of disk-based devices, which write backup data into files residing on the disks. The ZDB concepts are not topics of this white paper; instead the concepts of backup to disk-based devices will be discussed in more detail.
Many applications and databases frequently make small changes to existing files or produce many new files containing business-critical data throughout the working day. These files must be backed up immediately to guarantee their data will not be lost. This requirement means that a fast medium capable of storing large amounts of data without interruption is necessary for storing data. Disk-based storage media has become increasingly cheaper in recent years. At the same time, the storage capacity of disks has risen. This has led to the availability of low-cost, high-performance single disks and disk arrays for storing data.
Disk backup (also known as disk-to-disk backup) is becoming ever more important. In the past, tape storage was the favored medium for backup and restore because of its price and effectiveness in meeting disaster recovery requirements. Today, more businesses are augmenting their tape storage backup solutions with faster disk-based backup solutions. This ensures faster data backup and recovery.
Backup to disk-based devices—benefits
There are many situations in which it is advantageous to use disk-based devices when performing backups. Disk-based devices are, in fact, specific files in specified directories, to which you can back up data instead of (or in addition to) backing it up to tape. The following list indicates some situations in which disk-based devices are particularly useful:
• Many applications and databases continuously generate a high number of files or changed files, containing business-critical data. Under these circumstances, it is necessary to continuously back up the concerned files to guarantee the capability of restoring them without data loss.
• In these environments, tape devices typically have to operate in stop/start mode because they do not receive a constant data stream. This may result in the tape device limiting access to the
concerned files. In addition, the lifetime of the backup device may be greatly reduced. In this case, a backup can alternatively be performed to any disk-based device, overcoming the limitations described. As a short-term backup solution, this is adequate in itself. If a longer term backup solution is required, the data in the disk-based devices can be moved periodically to tape to free up the disk space. This process is known as disk staging.
• In environments that have fast, high-capacity disk drives and slow tape drives, you can shrink the backup window by performing backup to disk-based devices first and moving the data to tape later.
• Disk-based devices are useful for providing fast restore capability for recently backed up data. For example, backup data could be kept in file devices for 24 hours to enable fast, convenient restore without the need to stream data from tape first.
• Mechanically, a disk-based device is quicker to use than a tape. When using a file device, there is no need to mount and unmount a tape. When backing up or restoring a small amount of data, a disk-based device is quicker because it does not need the initialization time that a tape drive requires. With a file device, there is no need to move a robotic to load or unload media, which consumes more time in a small backup or restore. This is especially true when restoring from an incremental backup.
• The risk of media problems such as faulty tapes and tape mounting failures are reduced to a minimum. The availability of RAID disk configurations provides protection of data in cases where a disk fails.
• Overhead costs are reduced because there is no need for tape handling, for example, during the performance of incremental backups to disk.
HP Data Protector Software offers three different device
HP Data Protector Software has a selection of devices that are designed to do backup and restore to and from disks. These devices are referred to as disk-based devices because they are designed to back up data to disk as opposed to tape. The devices vary in their functional sophistication and expected uses, and include:
• File device (standalone)
The file device is the simplest disk-based device. It is a standalone device and it has to be
configured manually. It consists of a single slot to which data can be backed up. It is not possible to change the properties of the device after it has been created. The recommended maximum capacity of data that can be backed up with the standalone file device is up to 2 TB, if this file size is
supported by the operating system on which the device is running. • Jukebox
The jukebox device is a logical equivalent of a tape stacker. It contains slots whose size is defined by the user during initial device configuration. This device is configured manually. The jukebox properties can be altered while it is being used. Each slot in the file jukebox device has a maximum capacity of 2 TB. The device’s maximum capacity is equal to: number of slots x 2 TB
• File library device
The file library device is the most sophisticated disk-based device. It consists of multiple slots to which you can back up data. It is designed to execute unattended backup and restore of large amounts of data. It can be automatically configured using a wizard in the Data Protector GUI. As with the Jukebox, the recommended maximum storage capacity of this device is limited only by the amount of data that can be stored or saved in a file system by the operating system on which the file library device is running.
Out of the three disk-based devices, the file library device is recommended for use as an unattended backup device.
What is a file library?
The file library is a new device type introduced with HP Data Protector Software Version 5.5. It is a group of files in one or more configured directories to which you back up data instead of writing to a tape. The files contained in the file library are called “file depot.” There is no maximum capacity for the file library device that is set by Data Protector. The only limit on the size of the device is
determined by the maximum size of a file, which can be saved in a file system on the operating system on which the device is being run. For example, the maximum size of the file library device running on Linux would be the maximum size of a file you can save on this operating system. You specify the capacity of a file device when you first configure the medium. It is possible to re-set the sizing properties of the file library at any time during use of the device in the Data Protector GUI. The file library device can be located on a local hard drive, or even on a network share, as long as Data Protector knows its path. The directory path is defined at configuration of the file library device. However, it is recommended to use a local disk or a disk in SAN. Disks connected by way of NFS/CIFS links provide only a slow connection and are sometimes unreliable.
A file library consists of configured directories that include files where the data is stored. The directories are configured at the initial configuration of the file library device. The files inside are called “file depot” and they are created each time a backup or copy session is made to the file library. If the amount of data being backed up is larger than the maximum file depot size, Data
Protector creates more than a single file depot for a backup session. The backed up object will span over two file depots. A file depot is equivalent to a tape media in a slot, whereas the directories represent the repository (slots) part of a library. As a consequence, many of the known media
operations can be applied, for example, scan, format, recycle, export (non DFMF library), and so on. However, some operations are not available, for example, eject.
The name of each file depot is a unique identifier that is automatically generated by Data Protector. It looks similar to the Data Protector media ID, but actually it is not a media ID, instead just a unique file name. For example, (including path 80 character filename limitation):
Since each file depot contains backed up or copied data, a corresponding DCBF file keeps the detail catalog information for it in the IDB. Thus, for each file depot a corresponding DCBF file exists, providing a logging level or catalog protection period is specified (default).
The size of file depots is defined when you initially create the file library device. During this process you specify all sizing properties for the device, including the maximum size of the file depots (see Figure 2). The sizing properties of the file depots, although only entered once, are globally applied to each file depot within its directory. If the size of data to be backed up within one session is larger than the originally specified file depot size, Data Protector automatically creates more file depots until the allocated disk space for the file library device has been consumed.
On Windows, the maximum recommended file depot/slot size is 5 GB, although the standalone file device has been tested on Windows with file depots of up to 600 GB. On HP-UX, the maximum allowed file depot size is 2 TB. However, for best performance a 5 GB depot size is recommended.
Analog to the file jukebox file drives can also be created; these are called “writers.” The naming convention for the writers is:
<file library name>_Writer<number>
For each newly created file library, by default there will be a new media pool created with the naming convention <library name>_MediaPool. The user can change this setting to any other existing mediapool of type “file.”
Distributed file media format (DFMF) file library
With HP Data Protector Software Version 6.0, a new media format is introduced—distributed file media format (DFMF). This format can only be used with the Data Protector file library and is by default not enabled. For enabling this DFMF format, the appropriate option needs to be selected (see Figure 3).
Without this format Data Protector writes all data and catalog segments into one file. This is done per session, hence each session creates its own file. With the new media format, data blocks are written into different files. This is done for each file, bigger than the used block size (default 64 KB).
Therefore, for each backed up file, a dedicated file on the file library is created, which holds the data blocks.
If a consolidation session is performed on backups that are all located in the same file library, the data that will be consolidated is already stored in one or more media files. The new DFMF concept tries to reuse those files, hence instead of copying the data blocks, they are only referred by way of pointers. Therefore, consolidation sessions, creating virtual full, do not copy the files hosting the data blocks. Instead, the new session only refers to them by way of pointers. Note that only consolidation sessions are using pointers; normal backups, both full and incremental, are always creating new data block files.
Figure 4 shows conceptually the difference between the conventional and the new DFMF format for the Data Protector 6.0 file library. Instead of putting all data blocks into one file, the new DFMF creates several files on the file library. For each file that is backed up, an own file is created inside the file library to host the data blocks. The parent medium file, storing all catalog information, is using pointers to find the data segments.
Figure 4. Difference between conventional and new DFMF format
Enhanced incremental backup (Incremental forever)
With conventional incremental backup, the criterion for determining whether a file has changed since a previous backup is the file’s modification time. There are cases where this criterion is not effective. For example, if a file has been renamed, moved to a new location, or if some of its attributes have changed, its modification time does not change. Consequently, the file is not backed up in an incremental backup. Such files are backed up in the next full backup.
With enhanced incremental backup, Data Protector 6.0 introduced its own mechanism to reliably detect whether a file has been changed and therefore should be put into the incremental backup. Enhanced incremental backup reliably detects and backs up renamed and moved files, as well as files with changes in their attributes.
Use cases for enhanced incremental backup include:
• To ensure incremental backup of files with changes in name, location, or attributes • To eliminate unnecessary full backups if some of the selected trees change
How does enhanced incremental work in Data Protector?
The first full backup with enhanced incremental backup enabled in the file system options of the backup specification (see Figure 5) creates two files for each directory on each client to be backed up. Both of these new files will contain a hash-key, one for the directory and the other for all the files of this directory. Additionally a timestamp is stored.
Figure 5. Enabling enhanced incremental backup
The hash-key contains the properties of the file. This information allows Data Protector to detect nearly all changes to the files and thus it is able to add all the modified files into an incremental backup job. This is done by comparing the stored hash-key with the current hash-key, generated whenever an incremental backup is done.
Note that the hash-key does not contain the ACL information. Therefore the enhanced incremental backup detects changes on file permissions not by the hash-key and must still rely on OS flags, like attribute flag on Windows.
Incremental forever paradigm
The incremental forever paradigm means that except for the first backup, where a full is performed, only incremental backups are executed. This concept presents the most efficient way of backing up only changed data.
However, without object (backup) consolidation, the restore process would last far too long, since nearly all backup sessions would have to be restored as separate objects. Due to this behavior, regular full backups are required.
Object (backup) consolidation removes this drawback. After the first full backup, you employ Data Protector’s new incremental forever technology. To prevent the incremental forever paradigm, Data Protector 6.0 has introduced the concept of object (backup) consolidation into synthetic full backups or space-efficient virtual full backups.
The Data Protector object consolidation functionality enables you to merge a restore chain of a backup object into a new, consolidated version of this object. Using this functionality, you no longer need to run full backups. Instead, you can run incremental backups indefinitely and consolidate the restore chain as needed. During the object consolidation session, Data Protector reads the backed up data from the source media, merges the data, and writes the consolidated version to the target media. The result of an object consolidation session is a synthetic full backup of the specified object version.
If a file was removed between two incremental backups, the consolidated session will include the file.
Synthetic backup is a backup solution that eliminates the need to run regular full backups. Instead, incremental backups are run, and subsequently merged with the full backup into a new, synthetic full backup. This can be repeated indefinitely, with no need to run a full backup again. In terms of restore speed, such a backup is equivalent to a conventional full backup. With a synthetic backup, all blocks (data and catalog information) are copied to a new media (see Figure 6).
Figure 6. Object consolidation concept
Figure 6 shows how the restore chain is consolidated. The restore chain, consisting of a full and three incremental backups, is consolidated into a new full, named synthetic enhanced full.
After a consolidation one session with type full (synthetic, enhanced) is listed inside the restore GUI. This session represents the incremental backup, used for the consolidation, and the consolidation itself.
Space-efficient synthetic full backup (virtual full)
HP Data Protector Software Version 6.0 introduced the possibility to perform a space-efficient synthetic full, also called a virtual full backup. By default a synthetic full copies all blocks (data and catalog information) to a new medium. With a space-efficient synthetic full, or virtual full, the data is not copied. Instead pointers are used to refer to already existing data blocks. As a result, the consolidation takes less time and avoids unnecessary duplication of data.
The following prerequisites must be fulfilled to perform a synthetic or virtual full backup:
• All the backups that will be consolidated were performed with the enhanced incremental backup option enabled.
• All incremental backups that will be consolidated reside in the same file library.
• The restore chain must be complete, meaning that all the object versions that comprise it have the status Completed or Completed/Errors and all the media holding these object versions are available.
• The necessary backup devices are configured and the media prepared.
• A Media Agent that will participate in an object consolidation session is installed on every system. • The appropriate user rights for starting an object consolidation session (Start backup specification)
• To perform a virtual full backup, all the backups source (full, incremental) and target (virtual full) must reside in the same file library that uses DFMF.
VLS Automigration option
Automigration is an automated copy process without putting additional load on the SAN or the backup application, like HP Data Protector Software. It means that that the VLS behaves like an echo/smart copy engine that migrates the data from the virtual cartridges on disk to a physical tape library or another VTL which is attached to the VLS device.
VLS Automigration data copy methods
The VLS Echo Copy method is performed by the VLS without any interaction from Data Protector. The data is asynchronously copied to the physical tape that belongs to a dedicated physical library connected to the VLS. This copy method creates a bit-for-bit copy which implies that Data Protector would not be able to distinguish both media.
The other Automigration data copy method is Smart Copy. This copy method is also performed by the VLS, but it is initiated and controlled by Data Protector. In Data Protector terminology it is called ‘Media Copy’. This is not a bit-by-bit copy as the tape header of the target media is different. So, created tapes can be distinguished and media management is enabled. Such tapes created with Smart Copy have the Data Protector format and are readable with every compatible tape drive that is configured in Data Protector.
How to integrate and configure Automigration in Data Protector
HP Data Protector Software Version 6.1 enhances the existing media copy functionality by introducing an Automigration option. This allows the migration of backed up data from the HP StorageWorks Virtual Library System (VLS) to a dedicated physical tape library or another VTL that is directly connected to the VLS through Fiber Channel. The VLS device has exclusive access and control over the physical library.
As this physical library is not visible for Data Protector, the VLS shows all slots of the physical tape library, which are associated with the smart copy services, as extended functionality/ special slots (see Figure 7 for VLS Automigration dataflow and device configuration in Data Protector).
Figure 7. VLS Automigration dataflow + device configuration in Data Protector
VLS Automigration dataflow
1.Backup from backup server or media server to VLS 2.Tape to tape copy
duplicates the data from VLS directly to the tape library 3.Tape is physically
taken off site
VLS Tape library
Data Protector backup server
Destination library can be a VTL, too.
Smart Copy Pool for physical tape library Imported VLS Device
• Configuration of a dedicated physical library on the VLS (under the new Automigration tab on the Command View VLS as can be seen in Figure 8)
• Smart Copy Pool Creation for this dedicated physical tape library : 1. Click on
2. Under “Destination Libraries, select “Media Pools” of the of the connected physical tape library
3. Click on
4. Fill out the required fields and click the submit button for Smart Copy Pool Creation
For further details about Automigration configuration on VLS side, please go to
http://www.hp.com/go/VLS Figure 8. VLS configuration
Data Protector configuration
• Installation of the Data Protector component “VLS Automigration on the client machine. • Import the VLS as the new client type “VLS device” into Data Protector
• During import operation, the IP address or hostname, username and password needs to be entered in order to gain the access to the CIMOM (Common Interface Model Object Manager) running on a VLS device.
• Enabling Automigration functionality by setting the appropriate option
• Activate “smart media copying” by using the existing media copy functionality Figure 9. Data Protector configuration
Import of VLS as client type ‘VLS device’
Enabling Automigration CIMOM configuration
How is the Automigration initiated by Data Protector
With Data Protector 6.1, the existing media copying functionality is used for triggering the smart/media copy process as follows:
• Automated smart/media copying: takes place after the completion of a backup session (Post-backup) or at a specific time or at regular intervals (scheduled)
• Interactive smart/media copying creates a copy of a medium containing the backed up data and can be started on demand at any point in time
VLS Automigration advantages
The VLS Automigration integrated into Data Protector brings the following benefits:
• Easy management, as smart copies are managed as standard Data Protector media copies. This means that Data Protector tracks the status of copy operations and monitors copy sessions.
The information about the smart/media copies is stored in the IDB
• Increased backup performance and significantly decreased backup window. The fast primary backups to the VLS disk-based virtual tapes are made with minimal impact on your
environment. Smart copying takes place as a secondary task without causing any disruption to the application performance.
• Additional protection against data loss due to the existence of multiple copies on disk and tape.
• The ability to create smart copies allows you to keep your data available for restore or data archiving for longer periods of time without exceeding the capacity of a virtual library. • Fast and reliable restores using the Data Protector restore functionality.
• Copies through Automigration can only be done between slots and copy slots of the same VTL
• After copy process, source and destination tape are made non-appendable. This is the same as for the usual media copy
• Media in the physical library can only be accessed through VLS
• Media within the copy slots cannot be used for other operations like backup and restore. Further information and consideration regarding the configuration and setup can be found in the VLS documentation and Data Protector’s manuals.
VLS versus Data Protector file libraries
The VLS should not be confused with Data Protector file libraries. Both are disk-based backup
solutions, but the VLS is a hardware solution, and Data Protector file libraries are a software solution. The VLS has the following advantages over Data Protector file libraries:
• VLS tape drives can be shared among multiple servers in a SAN environment just like physical tape drives.
• The VLS is optimized for sequential I/O and therefore provides better backup performance. • VLS tape drives appear as tape devices to the server and therefore will not be included in backups
or scanned by virus scan.
• VLS tapes can be imported into a Data Protector cell in the event that the cell manager is lost; file libraries cannot.
The following comparison was taken from the VLS customer presentation:
• Choose Data Protector Advanced Backup to Disk when any of the following are true: – You want to use existing storage in your SAN or locally attached storage.
– You have relatively few SAN hosts writing to disk. – Your environment is LAN only.
• Choose the HP StorageWorks Virtual Library System when any of the following are true: – You have many SAN hosts writing to disk.
– You want to use compression.
Data Protector GUI wizard
To make the creation and configuration of a file library as easy and user friendly as possible, a new GUI wizard has been added, which guides the user through the few required steps (see Figure 10).
Figure 10. Data Protector GUI
Automatic and intelligent space management
An important difference to a file jukebox is that with a newly created file library, no slots/file depots will be created. They will automatically be added into the file library during the usage. The customer has only to care about the disk space needed. By default all file depots will be non-appendable. This is very useful for the efficient disk space management. Only one session will be stored in one (or more) file depot. As soon the protection of the session expires, the file depot can be re-used. In cases where the customer has sessions with a small amount of data, backup of logical and archive logs, the media usage policy of the media pool should be changed to appendable.
Improved disk full handling
In the past during writing data into the file depot, there was a possibility that there was no disk space left to complete the task. This has been solved through the pre-allocation of that amount of disk space, which is needed to complete the write task, in particular to complete the write of the catalog segment.
Use case—Disk staging
The concept of disk staging is based on backing up data in several stages to improve the
performance of backups and restores, reduce costs of storing the backed up data, and increase the data availability and accessibility for restore.
The backup stages consist of backing up data to media of one type and later moving it to media of a different type. The data is backed up to media with high performance and accessibility, but limited capacity (for example, system disks). These backups are usually kept accessible for restore for a period of time when a restore is the most probable. After a certain period of time, the data is moved to media with lower performance and accessibility, but high capacity for storage, using the object copy functionality.
Figure 11. Disk staging example
Some use cases where a file library as part of a disk staging concept is very useful include:
• Continuous backup of transaction log files (no overhead through media load/unload and for tape drives there is no issue with start/stop mode)
• Backup of slow clients without multiplexing • Tapeless backup of branch offices
• Working similar to a virtual tape library Restore:
Fast restore from disk if data still available there
direct restore from tape Disk Agent
New file library license: B7038**
Advanced Backup to Disk Licensing (B7038AA/BA/CA)
• Includes the license-to-use (LTU) for 1/10/100 TB of backup disk storage. • Required once per terabyte (TB) usable native capacity of backup disk storage.
• Usable native capacity of a Data Protector file library is the size on disk of all files used for the file library, as reported by the file system.
• The backup disk storage can be distributed over multiple disk arrays and systems.
• Does not require any drive and library LTU. Drive and library licenses are required for file devices, but not for Advanced Backup to Disk. In the same way, Advanced Backup to Disk cannot be licensed with drive and library licenses.
• It does not matter whether UNIX or Windows powers the backup disk.
• The Advanced Backup to Disk license is required to back up to a Data Protector file library or a VTL.
HP Data Protector Software licensing using a VTL library
There are two ways to use a VTL with Data Protector. It is possible to choose whether to use the Advanced Backup to disk or tape drive licensing model. Within one VTL, both concepts must not been mixed.
• Drive/Library extension approach
Using the traditional drive extension licensing practices, you could license each individual virtual drive with the UX/SAN/NAS Drive Extension (B6953AA). The Virtual Libraries that you have created to house these drives are fully functional up to 60 slots. If the 60-slot limit is exceeded, then library slot extensions would be required—61–250 slots (B6957BA) or the unlimited slot license (B6958BA).
Using the drive extension approach can be done but it might limit your availability to the VTL because of the lack of licensing. This could potentially affect performance by having too much data and not enough devices available to stream to.
• Capacity-based licensing approach
Using the Advanced Backup to Disk licensing ((B7038AA/BA/CA 1TB, 10TB, 100TB), the usable native capacity of a virtual tape library (VTL) need to be licensed. This is the size on disk of the virtual tape library consumed by all protected Data Protector backups as reported by the VTL. Using this licensing model, the customer can configure as many drives and libraries as the VTL vendor allows. In the case of the HP VLS Virtual Libraries, 64 drives in 16 libraries can be created. This method is more favorable because you are only limited to the capacity of the licensing you have purchased. You can configure each device to back up a single object, allowing high-speed sequential backup of your data.
HP Data Protector Software Advanced Backup to Disk licensing works on a per-terabyte basis. However, due to the size on disk licensing concept, compression rates and de-duplication rates do not need to be considered.
In case this license has been purchased before July 1st, 2008, HP is fully committed to protect investments. This means you can choose to use this license for the VTL under the old licensing terms: “Usable native capacity of a VTL is the space occupied by protected backups and protected backup
Continuing with the previous model only makes sense in case you do not use compression or deduplication technology. Otherwise, you get a higher value if you use previously purchased licenses under the new licensing model.
This capacity enhancement is only available to HP Data Protector Software customers who deploy a VTL library utilizing the Advanced Backup to Disk Licensing extension.
To utilize the capacity-based license for a VTL, select the Virtual Tape Library option when configuring the SCSI device (see Figure 12).
Figure 12. Configuring capacity-based licensing model for a VTL
Summary and conclusions
• VTLs integrate into HP Data Protector based on the size on disk licensing concept without
considering compression rates and de-duplication rates when capacity-based licensing is invoked. • Disk staging acts as a buffer allowing media drives to operate at maximum speeds and provide the
option to do automatic data replication during off-peak hours. This technique is highly
recommended when backing up numerous small files to prevent poor transfer rates to tape drive. • Single file restores are executed with an excellent performance by disk technologies. This is very
helpful for selective file restores (particularly multiple times) where time is an important issue. No tape must be loaded and positioned, which is a major advantage against tape technologies.
For more information
• HP Data Protector Software
• HP StorageWorks Virtual Library System (VLS)
• HP Performance Assessment Tools
• Library and Tape Tools
Technology for better business outcomes
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