Some of you may be aware of a scenario in which the reclamation of Exchange 2010 database whitespace during item deletion or truncation is not as great as expected. So why is this a problem for Enterprise Vault customers?
Archiving data from a mailbox will frequently invoke either a deletion or truncation request to the Exchange server. If Exchange is not fully honouring this request then the database from which a customer is archiving will continue to grow as pending whitespace reclamation requests are not processed fully and available whitespace is not recognised.
The good news is that Microsoft have recognised and now resolved the issue: http://support.microsoft.com/kb/2621266
So what was the problem?
In summary the primary complaint was that in some cases Exchange 2010 customers were noticing that their mailbox databases were continuing to grow even though archiving was taking place and items were being archived as normal. The root cause of this was actually down to how Exchange reclaims whitespace and specifically the changes to this process in Exchange 2010. Modifications to the Online Defragmentation process caused, in some cases, whitespace to not be reclaimed for re-use essentially making that space unusable.
MS have now issued a fix which corrects the action of Online Defragmentation allowing customers to reclaim the excessive whitespace that has been building up in their databases.
For more information I highly recommend a read of the following technote: http://www.symantec.com/business/support/index?page=content&id=TECH164949&cache=refresh and my colleague’s blog here: http://www.symantec.com/connect/blogs/exchange-2010-whitespace-reclamation
Alex Brown
