Browse Prior Art Database

A Method of Application Log Backup and Recovery When Using a Virtual Machine Snapshot

IP.com Disclosure Number: IPCOM000224388D
Publication Date: 2012-Dec-17
Document File: 8 page(s) / 159K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method to recover application data from a virtual machine snapshot and a legacy log backup. The novel approach specifically uses the legacy log backup after the snapshot and then prevents the database from self-recovery after a full-VM restore.

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A Method of Application Log Backup and Recovery When Using a Virtual Machine Snapshot

When taking a snapshot of a virtual machine, (VM) it is necessary to perform application quiescing so that the application data is consistent on the snapshot. The quiescing could be done via scripts that run before a snapshot is taken or, in the case of Windows* guests, it could be done via Volume Snapshot Service (VSS). With VMware**, there is an infrastructure to perform application quiescing with VSS but it has a few shortcomings. VMware infrastructure does not support sending a "complete" command to MS VSS framework in order to notify applications for backup completion. In addition, VMware notifies the VSS that the backup type is copy (instead of full, or incremental). This results in most applications' logs not being truncated after a VMware snapshot is taken. Additionally, some applications do not support log backups via VSS.

There is a need for a method to back up application logs outside of VSS infrastructure.

The problem occurs when a backup application backs up a VM that contains an application and the following two conditions are true:


• Application protection quiesces only database files, but not the transaction logs. These logs would need to be backed up and truncated using a non-VSS (legacy) method. For example by running data protection (DP) for Structured Query Language (SQL) log backup or an sqlcmd backup log command.


• After the restore of the VM, the databases are recovered automatically during VM startup. This makes restoring the transaction logs impossible. (The disclosure talks about the full VM restore, not VSS restore of parts of the VM.)

If the logs are not backed up or cannot be applied, there is no application point-in-time recovery available during the VM restore.

Current solutions include:


• Use an in-guest DP to back up application data. This requires installing a DP in the guest.


• Use in-guest application commands to back up the logs. There is a problem with where the backup of the logs is stored. They can be copied to an external disk or

just discarded. There is also an issue with how to apply the logs.

The solution is a new method to recover application data from a VM snapshot and a legacy log backup. The novel approach specifically uses the legacy log backup after the snapshot and then prevents the database from self-recovery after a full-VM restore.

With the implementation of the disclosed invention, during the backup processing, after the snapshot containing application consistent data has been stored, the following takes place:

1. Backup application executes an in-guest program that backs up application logs to local disk

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2. Backup files are transferred to the machin...