===== Quiesce operations and SQL backups =====

This is not really a VMware issue, however, we hit it when using vSphere Replication, because VR uses VSS Quiesce.

In this case, the customer was using Symantec to backup his SQL database, the database itself mind, not the VM, this is important.

When Symantec backups up the DB, it adds an entry in the /backupset/ table, marking the last backup timestamp, the next time it tries to backup, if compares what it has with the records in that table, if they match, go ahead, if not, errors and doom.

What does that have to do with anything I hear you ask.

Well, it turns out, that a VSS Quiesce operation will also update this table, so ANYTHING relying on VSS will trigger this, snapshots, VR VSS Quiesce, NTBackup...etc.

Like I said, not really a VMware issue.

The fix? Well you can ask Microsoft, I don't know how to tell VSS not to update the DB, that is beyond me, but I did find two Microsoft KBs that describe the issue.

  * [[http://support.microsoft.com/kb/951288|SQL Server records a backup operation in the backupset history table when you use VSS to back up files on a volume]]

  * [[http://support.microsoft.com/kb/903643|The Ntbackup.exe operation may break the differential backup chain of a SQL Server database and may invalidate the differential backups when you perform a snapshot backup of the database]]

Fix? What fix?