Installing and Configuring the Option › Configure VTLs to Function as Arcserve Backup VTLs

Configure VTLs to Function as Arcserve Backup VTLs

Virtual tape libraries (VTLs) are disk-based devices that are designed to behave like physical tape libraries. To allow Arcserve Backup to back up data to these devices, VTLs, you must configure the devices to function as Arcserve Backup VTLs.

Important! You should not configure standard physical libraries to function as an Arcserve Backup VTLs. The library's backup and data migration performance can be adversely affected when configured to function as a VTL.

Prerequisite Tasks

Before you can configure devices to function as VTLs, verify that the following prerequisite tasks are complete:

• The Tape Library Option is licensed.
• The VTLs are properly configured using Device Configuration.
• Arcserve Backup detects the VTLs.

To configure VTLs to function as Arcserve Backup VTLs

1. From the Administration menu in the Navigation Bar on the Home Page, select Device.

   The Device Manager window opens.

2. From the Server directory tree, locate the VTL.

   Right-click the VTL and select Library Properties from the pop-up menu.

   The Library Properties dialog opens.

3. Select the General tab.

   In the VTL (Virtual Tape Library) section, check the Library is a VTL check box and click OK. Arcserve Backup ignores specified media expiration dates when you select this option.

   The library is identified as a VTL in the Backup Manager, Destination tab.

   

   Note: If you do not want to identify a library as a VTL, repeat the above steps and remove the check mark from the Library is a VTL check box.

Specify the Block Size for Backups to Tape Libraries

Arcserve Backup lets you specify the block size for tape backups. This capability lets Arcserve Backup transfer more data per block to the device. Before you specify a larger tape block size, consider the following circumstances:

• The largest default tape block that Arcserve Backup can transfer is 64 KB. You can increase the tape block size to 128 KB, 256 KB, or 512 KB when using tape drives in your backup environment that support larger tape blocks.

  Note: See the device and host bus adapter (HBA) manufacturer documentation to verify that the device supports larger data transfers.

• Large block backups require HBAs that support large transfer sizes. When Arcserve Backup detects the HBA cannot support the data transfer size required for the larger block size, Arcserve Backup disables the larger block size and records an error message in the Tape engine log file.
• When Arcserve Backup overwrites or uses blank tapes, Arcserve Backup formats the media using the newly defined tape block size.
• When Arcserve Backup appends data to media, Arcserve Backup writes the appended data to the media using the block size originally applied to the media.
• For SAN attached libraries, verify that the HBA for all SAN member servers can support the transfer size that the tape block size requires. Backups to SAN member servers that do not support the larger transfer size usually fail.

To specify the tape block size for tape libraries

1. Stop the Arcserve Backup Tape Engine service on the backup server that you want to configure.

   Note: If the backup server is a SAN primary server, stop the Tape Engine service on the SAN member servers.

2. Open Windows Registry Editor and browse to the following key:
   • x86 platforms:

     HKEY_LOCAL_MACHINE\SOFTWARE\ComputerAssociates\CA ARCServe Backup\Base\TapeEngine 
     

   • x64 platforms:

     HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\ComputerAssociates\CA ARCServe Backup\Base\TapeEngine
     

   Locate the DEVICE# key for the tape library that you want to configure.

3. Under the DEVICE# key, create a DWord registry key named ForceBlockSize.

   Specify one of the following DWORD values:

   • 0x100 (256 KB)
   • 0x200 (512 KB)

   Close the Edit DWORD Value dialog and close Windows Registry Editor.

4. Restart the Arcserve Backup Tape Engine service on the SAN primary server and the SAN member servers.

The tape block size is applied to all of the drives contained in the tape library.