Let's say an Exchange DB exists on a 100GB drive. The DB itself gets up to 50GB on the first day, then users delete 10GB of data from their mailboxes over the course of the day. From my understanding: i. Online maintenance runs at the set interval > but what does this actually do in terms of whitespace? I've read around but not sure. As far as I understand, the online maintenance reclaims the space from the database and defragments the DB so that that whitespace ('free' space but within the DB itself) can be used by Exchange for more data, rather than expand the EDB file itself. ii. Online maintenance logs 1221 Event ID - this shows how much space Exchange has recovered from removing deleted items and now exists as whitespace in the EDB? That is, if offline defrag or mailboxes were moved, then this is the 'true' size of the DB? iii. How does this all work with SCR/CCR? Would I expect the EDB sizes on the DB on the target side to be the same as the size of the EDB on the source side? Or would they be this size minus the whitespace? iv. Is there any special way to treat whitespace with CCR/SCR? Normally, if it looks like the DB is getting too big for the drive and we know we have a lot of whitespace, we move the mailboxes to a spare store, delete and recreate the EDB, then move the mailboxes back and reseed. Can we do anything special on CCR clusters?

I , yes. II, Yes III, database files, whitespace etc. will be the same on target and source sinve everything is replicated with transaction log file copying. IV, I would not do offlive defrag or anything like it. If you feel a DB file grows to big, simply create a new SG+DB and move mailboxes to it, when done, remove the original SG and DB, no reason to recreate it and move mailboxes back. lasse at humandata dot se, http://anewmessagehasarrived.blogspot.com

Hi Lasse Thank you for answering. Some further questions. i. If Online Maintenance does NOT run/ complete for whatever reason, but items are still deleted from Outlook, what does this mean - that the deleted items are not purged from Exchange DB, although they are from a user's point of view? And how does this fit into the Deleted Item Retention/Dumpster feature? Will Online Maintenance only delete an item once the Deleted Item retention period has passed? ii. Point taken about moving mailboxes and recreating, I just wanted to check there was no feature within CCR that would mean we could avoid doing that.

If online maint. does not finish, it will continue where it stopped next time it starts. Deleted items/dumpster will not be deleted and marked as free white space until the retention period has passed. lasse at humandata dot se, http://anewmessagehasarrived.blogspot.com

Sure, but let's say Online Maintenance cannot complete on a DB for one reason or other. Am I right in saying that items passed their Deleted Item retention period are not purged from the DB and the DB will grow and grow? Is this a correct statement?

Correct. I would recomended to schedule online maint to do a full pass every night. if that isn't possible because of large DB files or whatever, try to make it complete once a week. Are you seeing a DB fikle that seems to be too big? Are you using an archiving solution replacing mail/attachment with a shortcut (aka, stubbing)? lasse at humandata dot se, http://anewmessagehasarrived.blogspot.com