Tip: Speed Up Snapshot Based Exchange DAG Backups (Veeam, CommVault, etc.)

I was struggling with performance issues with my Exchange 2013 DAG backups, mainly due to storage contention during the snapshot commit (remove snapshot). We have a node that contains only passive copies that we are using strictly for backup. I first tried to put the node into maintenance mode, which helped a little. I decided to try suspending the database copies during the backup and that made a huge difference.

Time to delete snapshot on passive node:
Normal: 1.5 to 3 hours
Maintenance Mode: 45 minutes to 1 hour
Mailbox Database Copy Suspended: 2-3 minutes!!!

Analysis:  Having a Node of the DAG that only contains passive copies of the databases helps reduce the impact of the backup on production users. Putting that node into maintenance mode prevents log files from being played into the databases, but they are still copied to the VM. Suspending the database copies prevents the logs from even being sent to the node, so there are very few changes during the backup. Since from what I have seen, writes typically impact storage performance in a greater capacity, the backup itself (just reading the data) goes pretty well, then deleting the snapshot (combining the snapshot data back into the main disk), really thrashes the storage. By minimizing changes to the disk during the backup, the snapshot commit has very little to do and goes very quickly.

Note: We use Veeam, and I tested a restore of an Incremental Backup using this method and was able to restore and view and restore emails with the Veeam Explorer for Microsoft Exchange with the database suspended.

I first tried this process manually and after it worked, I created a script to do the suspend and resume. My scripts are running on the Exchange Server itself, but you could certainly do this within the Veeam job under the Advanced Settings, Advanced Tab, then Job Scripts.

StartBackup.ps1
get-mailboxdatabasecopystatus -server passivenode|Suspend-MailboxDatabaseCopy -SuspendComment "Backup" -Confirm:$False

StopBackup.ps1
get-mailboxdatabasecopystatus -server passivenode|Resume-MailboxDatabaseCopy -Confirm:$False

Disclaimer: Attempt at your own risk. While I have tested this and it is working well for me, attempt first in a lab...yeah...like everyone has one of those. At the very minimum, run through your own backup/restore test to make sure it doesn't impact your ability to do the restores you want.