Running an Exchange 2007 backup using NT Backup under Windows 2003 has recently started failing, the fail could be quite quickly (just a few MB into the backup) or towards the end of the backup. The backup log reports the following message:

The ‘Microsoft Information Store’ returned ‘Some log or patch files are missing.’ from a call to ‘HrESEBackupOpenFile()’ additional data ‘C:Program FilesMicrosoftExchange ServerMailboxFirst Storage GroupE.log’

The ‘Microsoft Information Store’ returned ‘Functions called in an invalid sequence.’ from a call to ‘HrESEBackupClose()’ additional data ‘-’ The operation was ended.

A number of events are also displayed in the event log.

The first event, 8001 appear to be a generic error message and does not yield any clues as to the problem, however the next event is a little clearer.

Looking up Event 214 and error –521 offers this response

Error -521 = 0xfffffdf7 = = JET_errInvalidBackupSequence = Backup call out of sequence. This is a generic error with several causes and it has been seen when anti-virus software is running on the server and scanning the folder where affected databases were. The error has been seen when anti-virus software is scanning the M: drive. The error has been seen when 3rd Party backup software is running on the server and a problem with the software is causing the error.

The message suggests third part backup software could be running which is not the case in our scenario, also the anti-virus scan is not an issue.

There is a MS KB 820272 which indicates this problem could occur if you are backing up system state at the same time as the Exchange databases – however this too is not the case in our scenario. However, both of these explanations combined indicate this problem occurs if the files being backed up are affected during the backup process.

We are backing up a number of mail stores per backup run so the next step was to backup each store one by one to see which particular store might be causing the issue – only one of the mailbox stores was generating this error. A comparison of the mail stores followed – they are all on the same physical drive however the failing store has circular logging enabled, something that happened a short while back when the drive was running low on space. Disabling circular logging appears to have cleared this particular problem.