QSnap for the Quick Recovery Agent

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Configuration

Required Software

Extent Size

Configuration

The following must be done before using the Quick Recovery Agent with QSnap:

1. Verify that the computer in which you wish to install the software satisfies System Requirements for the Quick Recovery Agent and File System iDataAgent.
2. Install the required software.
3. Configure the software:

   Windows

   • When working with file systems other than NTFS, you must set an alternate COW Cache location on an NTFS volume. Increase the maximum size of the QSnap COW Cache to accommodate your disk configuration and usage. See Windows COW Cache for more information on COW Cache configuration.
   • After installation, it is highly recommended that you configure persistence for the volumes you are protecting. See Persistence for more information.

   UNIX

   • The COW Cache mount point is selected at the time of installation. See Unix COW Cache in the Overview - QSnap page for more information on supported COW cache configurations.
   • When you add a volume to a subclient content, it is automatically configured as a CXBF device. See CXBF Devices in the Overview - QSnap page for more information.
4. Configure subclient(s) and content. See Subclients - Quick Recovery Agent for more information.

Required Software

Windows

The following must be installed on the source and destination client computers:

• Quick Recovery Agent
• QSnap (this can be installed during the install of the Quick Recovery Agent)
• Windows File System iDataAgent
• MediaAgent (destination client only)
• To use the Quick Recovery Agent to browse and recover QR Volumes at the application level for Exchange 2000, Exchange 2003, SQL Server, or Oracle, one of the following iDataAgents must be installed:
  • Exchange 2000 Database iDataAgent
  • Exchange 2003 Database iDataAgent
  • SQL Server iDataAgent
  • Oracle iDataAgent

For a clustered environment, the Windows File System iDataAgent and QSnap must be installed on the physical nodes first. Then the Quick Recovery Agent and the Windows File System iDataAgent are installed on the virtual node.

Unix

The following must be installed on the source and destination client computers:

• Quick Recovery Agent
• QSnap (can be installed during the install of the Quick Recovery Agent)
• Unix File System iDataAgent
• MediaAgent (destination client only)
• To use Quick Recovery Agent to browse and recover QR Volumes at the application level for Oracle databases, the following iDataAgent must be installed:
  • Oracle iDataAgent

For more information and procedures, see Deployment - Quick Recovery Agent.

Extent Size

If performance is inhibited because of extent size issues, contact your software provider for more information about tuning your software for maximum performance.

Unlike a File System iDataAgent which backs up files, the Quick Recovery Agent (when using QSnap) copies extents on the source drive. The default extent size is 256KB, effectively dividing the source volume into 256KB chunks. The extent size can be configured to be larger than 4GB using the ReplicaExtSize and ReplicaExtSizeHigh registry keys. Every extent that contains data, is copied block-by-block. Therefore, a 256KB extent which contains 10KB of data will result in the entire 256KB extent being copied, including the empty blocks. Bear this in mind when considering both the condition of the data on a source volume (fragmentation) as well as the sizes of files and typical usage patterns, which may result in data scattered over the drive, and the impact this will have on both the speed and size of QR Volume creation and updates.  If for some reasons the extent size is required to be changed, see Change extent size for Replication Applications for more information on changing extent sizes.

For the QR Agent on Unix consider the following when changing extent sizes:

• Replica extent size must be uniform across source and destination computers.
• In a clustered environment, all the physical nodes must have the same Replica extent size.
• Replica extent size should not be larger than the size of the volume.
• The extent size can only be changed when the CXBF device is configured. Thus, to modify the extent size of an existing CXBF device, you must first deconfigure the CXBF device and then configure again.
• When configuring a CXBF device from Volume Explorer, the value entered must be a power of 2. Using a value which is not a power of 2 will cause the CXBF device configuration to fail. By default, the value is 4096; examples of acceptable values would be 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768, etc.

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