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We are running Exchange 2016, 14 Databases currently running on drive letters. We want to move to mount points, and as part of this, create new DBs and migrate all mailboxes (as this will also clear down any corruptions, white space etc.)

When performing mailbox migrations, I assume this increases transaction logs generated, but I'm unsure exactly where.

Take User A, located on MailboxDatabase1.

I migrate this user, via a normal Exchange 2016 migration batch to MailboxDatabaseMountPoint1.

Do the transaction logs increase on the source mailbox database log drive, or the destination, or both? Note, we will have separate log drives to the DB drives. I also read online that it generates the arbitration mailbox, is that on top of, or instead of the log drives for the associated databases? If so, do you advise enabling circular logging while this process takes place, even though this will take a number of days/weeks to complete. (Backups only run once a night, again, out of my control).

Sai Chandra Gadde
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Osyrus Solutions
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2 Answers2

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If you can tolerate the potential data loss of having to restore to the previous nightly backup, then yes, enable circular logging during the migration process. You should only need to do this on the mailbox database that hosts the migration arbitration mailbox.

If you can't tolerate the potential data loss of having to restore to the previous nightly backup then increase your backup frequency during the migration process to ensure that transaction logs are flushed more frequently so as not to fill up your log drives.

Personally, I'd opt enable circular logging for all mailbox databases during the migration.

https://support.microsoft.com/en-us/topic/large-transaction-logs-are-generated-when-you-move-mailboxes-in-exchange-server-2013-or-exchange-server-2016-administration-center-b0d99813-08f4-399d-5de7-15b53709ead7

joeqwerty
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  • Hi Joe, thanks. So do the logs only get stored on the arbitration mailbox? If so, could I just move that to a dedicated database and enable circular logging? Do logs build on the source or destination mailbox databases for the mailbox being moved? – Osyrus Solutions May 15 '22 at 16:45
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You could refer to the Mailbox migration best practices introduced here. enter image description here

joyceshen
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  • So why not just move then arbitration mailbox to its own database entirely, then setup circular logging on there. This avoids the need for circular logging on the DB we are moving mailboxes too? – Osyrus Solutions May 16 '22 at 06:42
  • Of course, you could do this. steps list here: https://www.alitajran.com/move-arbitration-mailboxes-in-exchange-server/ – joyceshen May 16 '22 at 07:51
  • Any update here about this issue so far? – joyceshen May 23 '22 at 07:09