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Exchange backup very slow

Created: 14 Nov 2011 • Updated: 06 Dec 2011 | 2 comments
liuyang's picture
This issue has been solved. See solution.

Hi, my master server is NBU 7.1 on Windows 2008 R2 SP1. We have two Exchange 2010 mailbox servers (both are Exchange 2010 SP1 on Windows 2008 R2 SP1). We have converted both mailbox servers to SAN media servers and connected them to the tape library (LTO4 FC tape drive) via FC.

When we do backups, it take very long to complete the backups. For example, we have one mailboxDB1 on mailbox server A. The size of the mailboxDB1 is about 500GB. It took about 2 hrs for the backup to start to actual write data to the tape. From activity monitor, it said the backup starts but then just hang there. After about 1 hrs, it start a sub job which shows file list of the mailbox DB. After another 1 hrs, it starts to write data on the tape.And the backup throughput is less than 10MB/s (normally only 7 ~ 8MB/s).

As the connection from the mailbox server to the tape drive is FC, we expect the throughput to be 30 ~40MB/s at least. May I know how to troubleshoot this? Thanks in advance.

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Mark_Solutions's picture

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

Authorised Symantec Consultant

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SOLUTION
Omar Villa's picture

I have see nbrb to take hours to assign a resource this.on 654 or prev versions, what nbu.level u are?

Omar Villa

Netbackup Expert

Twiter: @omarvillaNBU