Making Exchange backups faster

Recently, I was at a client doing an intervention on their Exchange and Active Directory infrastructure when, before doing some critical changes in the production environment, we had to do a full Exchange backup. At the time I didn’t know exactly how much information they had in their mailbox stores, but it turned out to be quite a lot.

Since time is money I remembered that we could have made things faster if we have tweaked NTBackup previously (yes, I love using NTBackup to backup Exchange stores).

If you read an article I wrote some time ago, 10 Tips to Optimize Exchange 2003 Performance (Part 2), you’ll notice that my 6th tip is about making Exchange backups faster. Basically you need to change some registry values under the key HKEY_CURRENT_USER\Software\Microsoft\Ntbackup\BackupEngine\ (if you don’t see the BackupEngine subkey you’ll have to run Windows Backup at least once):

Logical Disk Buffer Size = 64
Max Buffer Size = 1024
Max Num Tape Buffers = 16

These settings will boost data throughput from 640MB/min to 1200MB/min. This means that my waiting time at the client could have been reduced to a half! Of course I modified those keys immediately, but since the backup had already started, we didn’t benefit from that change.

In the article I also advise you to get an improved of version of NTBackup, which is now included in Windows Server 2003 SP1. This new version support the /FU switch that further improves the data throughput.

Using the /FU switch will also save you some time. I made some basic testing and measures with and without this new switch. The measures were made by backing up a 2GB file and the gains were between 23 and 33%, as you can see in the following table:


Without /FU

With /FU

Mirrored Write-Back



Mirrored cache disabled



Further reading:

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