Exchange backup very slow

[liuyang]

Hi, my master and media servers are all NBU 7.1 on Windows 2008 R2 SP1. I have 2 Exchange mailbox servers (NBU 7.1, Exchange 2010, Windows 2008 R2 SP1). Both mailbox servers are media servers and connected to FC LTO4 tape drives. We back up DAG DBs (no GRT backups). The size of full backups is about 1.5TB and it takes around 14 hrs to complete. We think the backups run too slow. The avg throughtput for FC LTO4 tape drive should be around 80MB/s. We expect the backups should be 200GB+ per hour. Now it is only around 100GB per hour.

Is there any way to improve the backup performance? Thanks in advance.

[Jackie007 · Accepted solution]

The delay between the job

The delay between the job starting and it writing to tape is whilst the snapshot is being processed.

If that is taking an excessive amount of time then check out VSS on the Exchange nodes.

It will also be verifying the databases during this time.

When it does eventually complete all of this and write to tape the throughput figure shown will be an average figure for the entire time it has been running, so although it shows 10 MB/s the actual write speed may be far higher than this as it has lost 2 hours for the preparation - can't say exactly without knowing the total time for  this backup.

You need to take a look at the Exchange Server to see how much load it is under - it may be better, if you are not already doing so, to take the backups via the passive node.

Also remeber you can use the NUMBER and SIZE DATA BUFFERS on the nodes to speed things up.

Look at Exchange itself first to see why the snapshot and processing is taking so long

Hope this helps

[Nicolai]

You should check out the "Backup planning and Performance tuning guide" - There is a whole chapter about  tuning a installation.

But I  just as Jackie007 definitely recommend configuring NUMBER_DATA_BUFFERS and SIZE_DATA_BUFFERS (that covered  in the Backup planning and Performance tuning as well - Page 122)

 http://www.symantec.com/docs/DOC4483

[Yogesh9881]

If file system backups from the Exchange client are running at a satisfactory speed, then most likely there is no performance tuning within NetBackup which will improve the speed of mailbox backups. 

Take a look at below URL...

http://www.symantec.com/business/support/index?page=content&id=TECH45477

[liuyang]

Thanks for your replies. I checked and found the file system backups also run at around 20 to 30MB/s. I also tested to run backups of a few Exchange mailbox servers. All ran at similar speed, around 20 to 30MB/s.

[Jackie007]

ok Great :)