Friday, December 28, 2012 10:14 PM
We backup a lot of data to our SAN nightly. These backup Jobs take Hours to complete and has caused random interuptions. Each night it causes delays in IO across everything that utilizes the SAN. Is there a way to throttle the backups and how much disk IO it uses?
Saturday, December 29, 2012 9:16 PM
To check issues from SQL server side take manual backups and try restoring to make sure no issues. If you are successful then the problem is completely from SAN. I guess you have identified the trouble form SAN. It could be an issue with RAID.
In that case you need to monitor on the SAN server. I am sure you get more help in the SAN forums.
Saturday, December 29, 2012 9:21 PMResource Governor *would* normally be the first place to look for this type of thing, but unfortunately it does not (yet) support IO throttling. Really your only option is to separate IO contention, offloading backups to another array (or storage subsystem). You can also look at optimizing your backup strategy thru spreading out during day, more use of diifferentials etc. Finally one tip, you can usually improve backup times by performing backups in parallel rather than doing sequentially. This will obviously saturate your IO channels, but should complete backups faster.
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Monday, December 31, 2012 6:14 PMAnswerer
Other than what Mark has said, the only thing I could think of is to use the MAXTRANSFERSIZE set to a very small number and BUFFERCOUNT also set to a very small number. Note that there are minimum amounts for each. I have no idea if it'll work or not, but that's the only way I can think of to do this (other than using windows resource management toolkit which I would NOT do at all).
Wednesday, January 02, 2013 2:48 AM
how you are initiating your backups to SAN. I come across an issue after a power failure. We are using net backup for our backups and restores from SAN. Recovering database to the same server fails for no reasons.
i managed to restore to some other server and then transferred to original server. scheduled backups are working fine. but restores have an issue to this server. not sure what causing the issue we tried all possibilities..
so it could be one of those unknown if you are using net backup.
monitor from SAN server....