Using Veeam we're backing up a passive mailbox database copy. The backup is valid, but log truncation never happens on the active server. The issue appears to be caused by a network timeout between the two servers as documented in this Symantec technote: http://www.symantec.com/business/support/index?page=content&id=TECH169681
A similar issue is also described here: http://social.technet.microsoft.com/Forums/en-US/exchange2010/thread/2b79c262-a208-4ebb-b514-4eecf5252547
Once the backup completes, we see the following error logged:
Log Name: Application Source: ESE BACKUP Date: 1/2/2013 8:52:28 PM Event ID: 964 Task Category: General Level: Information Keywords: Classic User: N/A Computer: PASSIVESERVER.awc-inc.com Description: msexchangerepl (2540) The surrogate backup to <ACTIVESERVER> has been stopped with error 0x6BE.
Error 0x6BE looks to be related to a failed remote procedure call. We're unsure of how this call is made though so we don't know what session timeout to increase between the two networks.
On the active server, we see an event logged once the backup starts. Exactly two hours later we see the event below saying that the backup has failed. We're assuming this is because the active server never receives notification from the passive copy that the backup was successful.
Log Name: Application Source: ESE BACKUP Date: 1/2/2013 10:02:31 PM Event ID: 914 Task Category: General Level: Information Keywords: Classic User: N/A Computer: ACTIVESERVER.awc-inc.com Description: Information Store (4372) The surrogate backup by ACTIVESERVER has stopped with error 0xC8000777.