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Does Microsoft SQL database performance degrade significantly during backups?

I have a situation here with a Microsoft SQL server running low on disk space.  Database and transaction logs reside on a 50 GB volume F: and backups go to 136 GB volume G:.  Both are getting full too quickly.  I suggested backing up to a network share and moving the tx logs to G: (the DB on F: itself is ~24 GB), but the interface programmer says that will increase the backup time from ~ 10 min to ~ 40 min and degrade DB performance.  Also that "the interfaces will slow to a crawl and data will not be received in a timely manner to the application."

I am skeptical of her assumptions.  Couple questions:

1) Does database performance degrade significantly during a backup.

2) Will a network backup necessarily increase the backup time that dramatically?  I know it depends on our network infrastructure, but this is all intrasite communication through 1 Gb interfaces.  I know for a fact that the bottleneck with our file/print cluster backups is the disks and not the network.

3) WRT interfaces slowing down (I'm assuming she meant because of the backup traffic), can't I just put another NIC in the box and route traffic to the remote share through that interface?
1 Solution
1.  No, it shouldn't.  So long as you're not putting the backup on the same drive as the data files and the log files, you should be fine.  The backups are dedicated to their own scheduler, so CPU time should be fine as well.
2.  It probably will make it slower, yes.  It has to put the data over the network.
3.  You can test it to see...it won't hurt anything to stop a backup.

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