Maintenance on our one and only mailbox database starts at 10 PM (22:00) every night of the week. Ends at 2:00 AM, according to the schedule. Database size: 8.7 GB. Takes 10 minutes. Target: shared folder on server in another building on other side of campus. Maintenance on our one and only Public Folder database starts at 10 PM (22:00) every night of the week. Ends at 2:00 AM Database size: 6 MB (used only for BES - Blackberry) This is what I see in the properties of the respective databases, looking at the customized maintenance schedule. Properties also shows that the "Last Full Backup" was 4:00 AM for the mailbox database and 4:10 AM for the Public Folder database. Yet... for the last three days, Event ID 9871 is appearing : There is an online maintenance overlap for database "First Storage Group\Mailbox Database". Please revise the online maintenance schedule. How can there be any overlap? Can maintenance, for some reason, continue beyond the 4 hour period that is allocated?

Sure this started only in the last 3 days? That's a warning that can be generally ignored.

Well, I filtered by EventID and besides one occurrence months ago, I had three in a row the last few days.

Hi Le, Which version of Exchange server do you use? Exchange 2007 or 2010? And service pack? If you are running Exchange 2007 SP1, as I know, this is a known issue. Please install the latest service pack and rollup. Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

Hi Le, Any updates?Please remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

Yes! EventID has not been recorded in Event Viewer since 2/24/2011, so it looks like I can indeed ignore it. Also, I am running Exchange 2007 SP2, so it is not due to SP1.

Strange... We are Exchange 2007 SP2 and it is happening for us too. We get the 9871, 1221 and the 704. If this is a known issue, and SP1 fixes it, why is it still happening in SP2? Is there another fix or something that we can do? We are scheduled for 1-5am and a backup kicks off at 6:00am. Does the process take longer that the 4 hour allocation? How can I check that? Earlier post states that it can be ignored prior to SP1, should it still be ignored post SP2?