Exchange transaction logs and EDB file behavior during full mail, calendar or PF resync. (4209244)

How full resync of mail, calendar or PF collection affects Exchange information store, in particular transaction logs and main database EDB file?

The behavior is determined by Exchange server architecture.

Every item within Exchange Information store is uniquely identified by PR tag property SourceKey that is serving the same purpose as GUID in AD. They can be seen with the help of low level MAPI editor like for example MFCMAPI from Microsoft:

http://support.microsoft.com/kb/291794

When mail, calendar or PF items are copied by Quest agents, their SourceKey valuesare preserved.

If Full Resync is performed on either mail, calendar or PF collection, it essentially means that everything that is currently residing on the source side within the scope of given collection will be extracted from source Exchange information store and sent to the target Exchange server. First all new messages are placed into transaction logs before they are committed to the database EDB file. When transactions are being committed Exchange Information Store skips the ones where SourceKeys are already in the database thus avoiding duplicates. Based on this logic full resync has the following effect on Exchange files:

1. Transaction logs will grow proportionally to the size of data came from the source.

2. Main EDB file will remain the same provided that all the data is already on the target.

IMPORTANT: If substantial EDB file grows is experienced this constitutes a problem and Microsoft support needs to be contacted. Please also see recommendations outlined in the following KB:

https://support.quest.com/SUPPORT/index?page=solution&id=SOL30640