Data management services provide several capabilities to optimize the performance of the storage system for remote users, support data protection and recovery, and simplify the management of data across a large number of storage systems. These services are discussed in the following sections.
6.3.1 BranchCache
BranchCache is a wide area network (WAN) bandwidth optimization technology. To optimize WAN bandwidth when users access content on remote servers, BranchCache copies content from main office or hosted cloud content servers, and caches the content at branch office locations, allowing client computers at the branch offices to access the content locally rather than over the WAN.
At the branch offices, content requested by a client is stored on servers configured to host the cache. Subsequent requests for the same content are served locally rather than downloading the content from the content server over the WAN link. This reduces network bandwidth usage and provides faster access to the files.
The topology for a BranchCache deployment is shown in (see Figure 18).
The source content in the main office is stored on BranchCache-enabled file servers, and has the File Services server role and the BranchCache for Network Files role service installed. These file servers use Server Message Block (SMB) to exchange information between computers.
The content cache at a branch office is hosted on one or more servers, which are called hosted cache servers, and each has the BranchCache feature installed with Hosted Cache Mode enabled.
Figure 18 – BranchCache Deployment
Deploy BranchCache for Network Files role:
To deploy BranchCache enabled content servers that are running the File Services server role, install the BranchCache for Network Files role of the File Services server role.
After the file server has been installed, enable Hash Publication for BranchCache for shared folders by using Group Policy or Local Computer Policy to enable BranchCache. In addition, enable BranchCache on file shares according to your requirements. During the configuration of the file server, specify whether BranchCache should publish the content for all, or a subset of file shares.
Deploy BranchCache feature – Hosted Cache Mode:
To install a BranchCache enabled, hosted cache server, enable the BranchCache feature.
After configuring the file server, configure the BranchCache Group Policy objects, enabling BranchCache, and specifying the BranchCache mode (Hosted mode). Also, specify the server from which to download data, the transfer latency threshold that triggers data to be cached, and the amount of disk space to allocate to the cache.
6.3.2 Data Deduplication
Use Data Deduplication to reduce the number of duplicate blocks of data in storage. Data Deduplication is much more effective in reducing the amount of data actually stored than Single Instance Storage (SIS), or NTFS file system compression used in previous releases of Windows.
General-purpose file servers can typically reduce storage capacity utilization by a 2:1 ratio.
Virtualization data (such as VHD files) can often be optimized to reduce storage capacity requirements by a 20:1 ratio.
When combined with BranchCache, the same optimization techniques are applied to data that is transferred over the WAN to a branch office. Faster file download times and reduced
bandwidth consumption can result.
With Deduplication installed, the Deduplication Evaluation Tool (DDPEval.exe) can be run to determine the expected savings if deduplication were enabled on a particular volume.
DDPEval.exe supports evaluation of local drives, as well as remote shares.
Deduplication was designed to support minimal hardware configurations, but as a general rule, deduplication requires 1 CPU-core and 350 MB of free memory per volume, and can process about 100 GB per hour (2 TB per day). Deduplication scales with additional CPU processor cores and available memory to enable parallel processing of multiple volumes. The actual speed of deduplication is dependent on CPU, disk I/O, memory, and available server resources at the time deduplication runs. Deduplication is designed to pause if the server starts to run out of resources to avoid impacting the server’s regular workload, so the busier the server is, the longer the deduplication process will take. Deduplication can also be scheduled to further reduce impact to the server.
Deduplication is not supported for files that are open and constantly changing for extended periods of time, or that have high I/O requirements, for example, running virtual machines on a Hyper-V host, live SQL Server databases, or active VDI sessions.
Deduplication will not process files that are constantly and exclusively open for write
operations. This means that there will be no deduplication savings unless the file is closed when an optimization job attempts to process a file.
Setting a hard quota on a volume root folder that has deduplication enabled is not supported.
However, a soft quota on a volume root that has deduplication enabled is supported.
Install the Data Deduplication role from the Add Roles and Features wizard. Configure Deduplication for a particular Volume as shown in Figure 19.
Figure 19 – Deduplication Settings Wizard
6.3.3 Distributed File System (DFS) and DFS Replication
DFS Namespaces – DFS Namespaces enables the grouping of shared folders that are located on different servers into one or more logically structured namespaces. Each namespace appears to users as a single shared folder with a series of subfolders, even though the namespace can consist of numerous file shares that are located on different servers and in multiple sites. Users can navigate the namespace without needing to know the server names or shares hosting the data.
DFS Replication – DFS Replication enables the efficient replication of folders (including those referred to by a DFS namespace path) across multiple servers and sites. DFS Replication uses an algorithm known as remote differential compression (RDC) to detect changes to data in a file, enabling only the changed file blocks to be replicated instead of the entire file.
DFS Replication must be installed on all servers that will act as members of a DFS replication group, and all servers in the replication group must be located in the same Active Directory
forest. Replication can only occur on volumes formatted with the NTFS file system (ReFS, or the FAT file system is not supported).
Install DFS Namespaces and Replication roles from File and Storage Services. Access DFS Management from the Server Manager Dashboard tools (see Figure 20).
Figure 20 – DFS Management
Create DFS Namespaces – Before DFS Namespaces can be used, create one or more
Namespaces using the “New Namespace Wizard” found in DFS Management. When creating the type of Namespace, keep in mind that DFS replication requires a domain-based namespace.
Once a namespace has been created, add shared folders to the namespace (Figure 21).
Figure 21 – Add Folder to a DFS Namespace
Create DFS Replication Group – Replication groups are created using the DFS Manager. Identify the folders to replicate, and create or identify target folders where replicated copies of shares will be copied. The amount of bandwidth used by DFS replication can be configured. By default, the wizard configures the replication group to synchronize continuously using all available bandwidth. This can be restricted, or scheduled to specific days or times of day.
6.3.4 Volume Shadow Copy Service (VSS)
Shadow Copies of Shared Folders provides point-in-time copies (snapshots) of files and folders that are located on shared resources. Snapshots are created at predetermined time intervals, and allow users to view shared files and folders as they existed at points of time in the past, however, shadow copies should not be considered as a replacement for regular backups.
Shadow copies can only be created on NTFS Volumes.
Volume Shadow Copy Services are built in to the operating system. Volume Shadow Copies are configured from within the Shadow Copies tab of the disk’s volume Properties dialog box (see Figure 22).
Figure 22 – Volume Shadow Copies Configuration
6.3.5 VSS for SMB File Shares
WSS 2012 introduced a new feature called VSS for SMB File Shares, which extends VSS and allows VSS-aware backup applications to create volume shadow copy snapshots of server applications that store data on remote SMB 3.0 file shares, for example SQL over SMB.
Windows Server Backup in WSS 2012 does not support VSS for SMB File Shares.
To use VSS for SMB shares, the following requirements must be met:
• The application server and file server must be members of the same Active Directory domain
• The File Server VSS Agent Service role service must be installed on the file server
• The File Share Shadow Copy agent must run in a security environment that has backup operators or administrator privileges on both the application server and file server
• The File Share Shadow Copy agent, and the application must run in a security
environment that has no less than read-only permission on the file share data that will be backed up
Install the File Server VSS Agent Service role from within the File and Storage Services roles.
6.3.6 iSCSI Target Storage Provider (VDS and VSS Hardware Providers)
When the WSS 2012 server is being used as a SAN gateway to external iSCSI storage, the iSCSI Target Storage Provider role services provide useful management capabilities.
The iSCSI Target Storage Provider role is available under the File and Storage Services role in Server Manager. Two storage providers are included with the iSCSI Target Storage Provider role, and are for remote Target management:
• Volume Shadow Copy Service (VSS) hardware provider
• Virtual Disk Service (VDS) hardware provider
Volume Shadow Copy Service (VSS) hardware provider – Similar to VSS for SMB Shares, the VSS hardware provider enables applications on a server that are connected to an iSCSI target (an iSCSI initiator), to perform volume shadow copies of data on the iSCSI virtual disk and which supports restoration at the LUN level. The VSS hardware provider is installed on the iSCSI initiator server that performs the backups, and the snapshots should be made from the iSCSI initiator.
Virtual Disk Service (VDS) hardware provider – The VDS hardware provider is typically installed on a storage management server, and enables older applications (such as Diskraid) that require the Virtual Disk Service (VDS) hardware provider to manage iSCSI virtual disks (external to the WSS 2012 server). VDS hardware providers are supplied by the manufacturers of hardware RAID devices and are not included in WSS 2012.
6.3.7 Windows Offloaded Data Transfers
Offloaded Data Transfers (ODX) enables direct data transfers within or between compatible storage devices without transferring the data through the host computer. By offloading the file transfer to the storage array, ODX minimizes latencies, maximizes array throughput, and reduces resource usage such as CPU and network consumption on the host computer.
The ODX environment must support the following:
• Only Windows 8 or Windows Server 2012 computers can initiate ODX data transfers
• File system filter drivers such as antivirus and encryption programs must support ODX
• ODX is not supported by the following file system filter drivers:
o Data Deduplication o BitLocker Drive Encryption
• Files must be on an unencrypted basic partition
• Storage Spaces and dynamic volumes are not supported
• Files must be on an NTFS formatted volume. ReFS and FAT are not supported. Files can be directly transferred to or from this volume, or from one of the following containers:
o A Virtual Hard Disk (VHD) that uses the VHD or VHDX formats o A file share that uses the SMB protocol
• The files must be 256 KB or larger – smaller files are transferred using a traditional (non-ODX) file transfer.
• The application that performs the data transfer must be written to support ODX. The following currently support ODX:
o Hyper-V management operations that transfer large amounts of data at a time, such as creating a fixed size virtual hard disk (VHD), merging snapshot, or converting virtual hard disks.
o File Explorer
o Copy commands in Windows PowerShell
o Copy commands in Windows command prompt (including Robocopy)
• Files should not be highly fragmented. Transfers of highly fragmented files will have reduced performance.
ODX is enabled by default in WSS 2012, but there are considerations when deploying ODX in a production environment. See Windows Offloaded Data Transfers Overview in Microsoft TechNet for more information.