Wednesday, March 21, 2012

Exchange Maintenance

I apologize for having disappeared for a short bit. I had some military training that pulled my attention from this blog for a short time. However, jumping back into the swing I'd like to make a short note about Exchange maintenance policy. For those of you that are using a backup solution utilizing VSS to complete file backups of the information store, this is of particular importance.

I have found that a lot of our clients have the maintenance cycle running as a daily occurrence. The logic of this move is that having the defrag occur that often is going to make the database more efficient and thus keep performance up for end users. The trouble is that if you attempt to use any backup solution that scans at the block level you are going to see a lot of change data. The consequence of this is that your backups will take longer than they should because you're sending over all these changed blocks that really aren't new data, but are flagged as such due to the shuffle. More often may not always be better.

A good real world example of this is a customer I had recently. They had a fairly small information store of around 50-60GB and were seeing backup jobs (using the 3X backup appliance) taking as long as 5-6 hours. Upon investigation it was found that each day the Exchange client was transmitting upwards of 4 GB of change data. I worked with the customer to reduce the scheduling down to twice a week over night (not conflicting with the backup window). The results of the change were staggering. After the first day we saw a 20% improvement, and after a week the job was down to 2 hours (60%).

Overall I suggest attempting to run maintenance less often if possible. Smaller deltas should speed up your backup solution, and cause less saturation on your infrastructure from the operation.

Ryan Koch
3X Systems

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