Zenith BDR, Exchange Server, and VSS
A few details related to how Zenith’s BDR solution works with Exchange Server and Volume Shadow Copy Service (VSS):
- For Exchange Server 2003 and 2007, the recommended best practice is to disable circular logging.
- To prevent the unfettered growth of Exchange transaction log, Exchange Server flushes its log files after each successful VSS-aware incremental backup, which, by default, is scheduled to run once per day at 12:30 am.
- With the release of StorageCraft ShadowProtect 3.2, we can now use VSS for all 15-minute incrementals (rather than just having a VSS-aware incremental backup take place once each day). In speaking with a Zenith BDR engineer, they caution against doing this for performance reasons, as both applications consume more resources as they flush their transaction logs. So, if the incremental backups aren’t impacting the performance of your Exchange or SQL server, then you can enable VSS on all incremental backups.
- On Small Business Server 2003 the Exchange VSS writer is disabled by default due to a potential incompatibility with the built-in NT Backup. Microsoft has published an article on how to turn on the Exchange writer for the VSS service.
Great post! There are a few confusing things, however, all centered around the lack of quiescence implied by doing a 15 minute backup without VSS (i.e., without StorageCraft.)
If the BDR software is doing block copies every 15 minutes but NOT using VSS, how is it that BDR can make sure that what is being backed up every 15 minutes is valid? In other words, if you want to recover from one of those 15 minute backups, how do you know for sure it’s going to work?
Going beyond Exchange, how does this work on the Windows file system at all? The 15-minute incremental backup is going to catch the blocks that have changed but not the cached file system changes, right? So how do you consistently recover from a 15 minute backup?
Posted by Mark on 10 August 2008 at 3:01 amMark,
Posted by John Ballinger on 28 October 2008 at 3:47 pmhave you received any further responses to this.
I’m looking for a definitive answer as to how and why BDR wi/daily VSS at 11:30PM only can be recovered and what points in time it can be recovered to.
We are running the BDR wi/VSS enabled once a day(the default) at 11:30PM which will cause the SQLServer log to be cleaned of all committed transactions when that VSS run is done.