Someone asked me recently whether rebuilding their mailbox archive index would mean that their Vault Cache would need to be reset also.
The answer is no, absolutely not, however I can understand where the confusion comes. If you’ve read the Virtual Vault best practices guide (http://www.symantec.com/business/support/index?page=content&id=TECH124700) then you’ll probably know that Vault Cache uses an archive’s indexes to perform its initial synchronisation so that it can download the MDC header cache. The same synchronisation process will then initiate the downloading of the content cache (if configured to do so).
So, why does rebuilding an archive’s index not interfere with the Vault Cache synchronisation process?
The answer is that Vault Cache only uses an archive’s index for its initial synchronisation - the first synchronisation it ever does. This process builds out the MDC header cache which is usually a one-time operation. Once this has been done all future synchronisation requests are incremental. Incremental Vault Cache synchronisations query the relevant Vault Store database to determine which items need to be added, removed, or updated. No further use of the archive’s indexes is needed.
It follows therefore that rebuilding an archive’s index will have no effect on Vault Cache’s ability to synchronise as this component is not used in the regular and periodic incremental synchronisation process. This applies to both 32-bit and 64-bit (EV 10 and above) indexes.
Hope that clears things up, it certainly did for me