Application-consistent backups

You can create application-consistent backups if your application instance supports Windows Volume Shadow Copy Service (VSS) or if your application instance supports application quiescing.

You can create application-consistent backups with ThinkAgile CP in the following scenarios:
  • Scenario 1: Your application instance runs on a Windows server, and it supports Windows Volume Shadow Copy Service (VSS)

    When you take a backup of a virtual machine (VM), the application instance acts as a VSS requester. VSS automatically quiesces the application instance before the backup is taken and "un-quiesces" it afterwards, making the backup application-consistent. If the application instance is a database, you can roll it forward by replaying the database logs.

  • Scenario 2: Your application instance provides a means to be put in a storage-consistent state (that is, application quiescing).

    For application instances that do not support VSS or for non-Windows applications, you can create an application-consistent backup with ThinkAgile CP by invoking a script that quiesces the application or puts it in a storage-consistent state. ThinkAgile CP provides the pre- and post-backup creation hooks to call such scripts.

    Note:

In scenarios outside of the two listed above, you will be creating a crash-consistent backup of the application, which is a point-in-time backup image. A point-in-time database backup cannot be rolled forward by replaying the database logs.

Invoke pre- and post-backup scripts

You can specify pre- and post-backup scripts that can be invoked in an application instance when a backup is taken. The scripts must be created with the following names and locations:
  • Windows pre-backup script:

    C:\Program Files\tacp\Hooks\PreSnapshot.bat

  • Windows post-backup script:

    C:\Program Files\ta\Hooks\PostSnapshot.bat

  • Linux pre-backup script:

    /etc/tacp/hooks/pre-snapshot

  • Linux post-backup script:

    /etc/tacp/hooks/post-snaphot

Example

To create an application-consistent backup for an Oracle database running on Linux, there is no VSS support. ThinkAgile CP can call your pre-backup script to put the database in a backup-consistent state by putting all tablespaces in backup mode, and then it can call your post-backup script to take them out of backup mode.

Example pre-backup script (which puts the tablespace in backup mode)

In the VM to be backed up, you can put the pre-snapshot script here:

/etc/tacp/hooks/pre-snapshot

sqlplus -s <admin>/<password> << EOF
set echo off;
set heading off;
alter database begin backup;
exit;
EOF

Example post-backup script (to return the database to a normal performance state)

You can put the post-backup script here:
/etc/tacp/hooks/post-snapshot
sqlplus -s <admin>/<password> << EOF
set echo off;
set heading off;
alter database end backup;
exit;
EOF