Saturday 12 July 2014

Exchange 2010 (journal) large mailbox move limit reached?

Journal mailboxes seem to have little said about them. I wonder how many people are using them. It would be good to store 50gb chunks of journal mailboxes on Office 365, but they are expressly not allowed. Now that would be a cheap solution!

The journal mailbox is on Exchange 2010 (SP3 RU6 at time of writing). It is pretty large - 440gb, 5.5 million messages all in one folder(!). I decided to move it to another 2010 database as part of an Exchange 2010 to 2013 migration. It crashed half way through with a complaint about too many bad items, so I ran it from PowerShell with a very high bad item count using the AcceptLargeDataLoss switch. (I note that the Exchange 2013 interface accepts large item loss and notes it in the log, which is better than forcing PowerShell usage). The move failed again about half way through after a day or so of running with a bad item count error again. I suspected this was a bogus error and I had reached the limit of what Exchange 2010 could move to another Exchange 2010 server in 1 mailbox. I worked round the problem by creating a DAG of the mailbox database in question to the same server, which was much quicker anyway as it copies the blocks of the database as opposed the messages individually. I could also have unmounted the database and copied it, then used database portability to it's new location, but preferred for it to be online/mounted all the time. The journal mailbox had to subsequently be moved to Exchange 2013 from 2010 and it was the moment of truth. Moment is not quite the word as it took several days to move it, but it moved without an error. It seems that Exchange 2013 has increased the limits for extreme mailbox moves. As Office 365 supports 50gb mailboxes I was hoping that it would work OK up to say 10 times that size, and that was the case. I need to think how to come up with a better journal mailbox partition mechanism for the longer term. Maybe one mailbox per year or something like that.

Until Microsoft come up with a solution that supports a journal mailbox system on Office 365 many people won't/can't move all their email infrastructure to the cloud.

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