ProxyHost with VSS - Truncating Exchange Logs

Overview

Batch Files for Exchange Log Truncation

• Example PreScan Batch File
• Example PostBackup Batch File

Configuring ProxyHost for Exchange Log Truncation

Considerations

Overview

The following section provides instructions for using VSS with a hardware snap engine and the ProxyHost iDataAgent to quiesce, unquiesce, and to eventually truncate the Exchange transaction logs. This is effected by first marking the last consistent log during the quiesce and saving that information to an ini file, which is referenced later to truncate the committed Exchange transaction logs from the quiesce time.

Batch Files for Exchange Log Truncation

A standard ProxyHost backup typically uses two batch files that perform the following functions:

• PreScan batch file
  • VssSnapshot multisnap (performs quiesce, snap, unquiesce)
  • VssSnapshot import (imports and mounts hardware snap to destination client)
• PostBackup batch file
  • Hardware snap cleanup

With Exchange log truncation added, the batch file adds the Exchange Log truncation functionality:

• PreScan batch file
  • VssSnapshot multisnap (performs quiesce, marks last consistent log in ini file, snap, unquiesce)
  • VssSnapshot import (imports and mounts hardware snap to destination client)
• PostBackup batch file
  • CVSnaptool –o truncateexchlogs
  • HW snap cleanup

Example PreScan Batch File

@REM Vars

SET VSS_INI_FILE_NAME=%windir%\temp\VSSsnap.ini

SET GalaxyBaseDir=<install_direcory>\Base

@REM snap

"%GalaxyBaseDir%"\vsssnapshot.exe multisnap %VSS_INI_FILE_NAME% -transportable -markexchlogs -esn <client_name> -vm <InstanceName*> -cn <ClientName> 

@REM import "%GalaxyBaseDir%"\vssSnapShot.exe vss import -verifyexchbackup -esn <client_name> -i %VSS_INI_FILE_NAME% -S <FQDM_of_source_computer> -vm <InstanceName*> -cn <ClientName>

Example PostBackup Batch File

Example POSTBACKUP (changes in blue)

@REM Vars (changes)

IF '%6'=='1' GOTO BACKUP_SUCCESSFUL

net send <client_name> backup phase did not complete successfully, so I won't execute the log truncation

exit 1

:BACKUP_SUCCESSFUL

SET VSS_INI_FILE_NAME=%windir%\temp\VSSsnap.ini SET GalaxyBaseDir=<install_direcory>\Base

@REM Destroy snap "%GalaxyBaseDir%"\vsssnapshot.exe unsnap -i %VSS_INI_FILE_NAME% -S <FQDM_of_source_computer> -vm <InstanceName*> -cn <ClientName> 

@REM Truncate section

"%GalaxyBaseDir%"\CvSnaptool.exe -o truncateexchlogs –g <storage group name> -ini %VSS_INI_FILE_NAME% -vm <InstanceName*> -cn <ClientName>

* InstanceName is the name used for a Proxy Host instance (by default it is Instance001). If multiple instances of Proxy Host are installed use the corresponding instance name, see Multi Instancing for more information.

Configuring ProxyHost for Exchange Log Truncation

Required Capability: Capabilities and Permitted Actions

To configure ProxyHost to truncate Exchange Logs:

1. Create the PreScan and PostBackup batch files, using the example scripts above. These files must reside on the backup host or primary host.
2. Install the ProxyHost iDataAgent on the production server, and the Windows File System iDataAgent on both the production server and backup host. Refer to Deployment - ProxyHost iDataAgent and Deployment - Windows File System iDataAgent.
3. Configure your environment; see VSS for the ProxyHost iDataAgent - Configuration.
4. Create a New Subclient, and configure subclient content. Click the Pre/Post Process tab of the Subclient Properties dialog box. In the PreScan field, type the path to the batch file file that contains those commands that are to run before each backup of the subclient, or click Browse to locate and select the batch file. Do the same for the PostBackup field.
5. Perform a backup. For more information, see Backup - ProxyHost.

Additional Suggestions:

• The vsssnapshot.log file will contain information about Exchange storage groups, creating and importing the snap (import information is mostly on the destination machine's vsssnapshot.log file.)
• The app eventvwr log will contain information on quiescing the correct Exchange storage groups.
• After the multi-snap operation, your ini file will contain information regarding the last consistent Exchange log file, etc., which will be used during the truncateexchlogs command.

Considerations

• The ini file must have same path and name in all scripts that reference it, although the variable name can be different.
• The cvsnaptool –truncate command is sensitive; certain normal cvsnaptool arguments are not necessary and may cause the Exchange log truncation to fail. A server name (–x) is not required, as it is stored in the ini file, nor is app name (–a) since Exchange is assumed.
• With VssSnapshot, storage groups are quiesced based on the volumes you specify when initially creating your ini file. Since it is a volume-based quiesce, it is recommended that you configure Exchange so that multiple storage groups do not share the same volume, and thus you can quiesce them individually.
• To selectively truncate storage groups when using VssSnapshot to quiesce them, you must use the –g switch with the cvsnaptool truncateexchlogs command. If you do not, the logs for all Exchange storage groups on that client will be truncated, regardless of which ones you actually quiesced.
• When using multiple ProxyHost subclients for your Exchange storage groups, the ini files for each group must have unique names; using the same ini file name for multiple subclients creates a risk of them getting overwritten or populated with the wrong info.
• PostBackup scripts are executed without regard to the success or failure of the backup attempt itself. However, the PostBackup script contains the log truncation step and it is very important that log truncation be executed only after a successful backup. This is ensured by utilizing a status variable, passed by the Job Manager to the PostBackup phase, in the 'if' statement in the example script to determine whether log truncation should run or not.