November 5, 2009 at 1:17 pm
Hi,
We have a SQL Server 2005 (SP3), Enterprise (64 bit) edition.
The data is on the H:\ drive. The Transaction Log is on the F:\ drive. Both H:\ drive and F:\ are SAN drives. Thus all the databases (user and system) have their data on the H:\ drive and their Transaction Logs on the F:\ drive.
There was a need in my organization to upgrade to a new SAN. The Vendor assured us that all the files (.mdf, .ldf etc.) would be transferred safely and there would be no problems.
So the following steps were done:
1. During off hours, SQL Server Service(s) were stopped.
2. Data was copied from the H:\ drive of the Old SAN to the H:\ drive and same for the F:\ drive.
3. The services were started.
Everything came back up. The databases worked fine and all the DBCC CHECKDB did not report errors.
I ran rebuid indexes, sp_updatestats and other scripts. Everything is fine. The users do not see any problems.
However, I noticed that backups are taking 3 times as long. We used to back up the databases to the local drive (C:\ drive not SAN). However, the backups now take 3 times as long. I tried creating new Maitenance Job for the backup. But the same thing happens. Backupups (Which is really BACKUP DATABASE TO DISK=... command) is still taking 3 times as long.
All the settings on the new SAN have been checked and double checked. No issues there.
Why is this happening? Should I have detached the databases and re-attached the databases instead of moving files to a new SAN, after stopping services.
Thanks
November 5, 2009 at 1:28 pm
What kind of disk SAN do you have?
November 5, 2009 at 1:34 pm
KP-249943 (11/5/2009)
Hi,We have a SQL Server 2005 (SP3), Enterprise (64 bit) edition.
The data is on the H:\ drive. The Transaction Log is on the F:\ drive. Both H:\ drive and F:\ are SAN drives. Thus all the databases (user and system) have their data on the H:\ drive and their Transaction Logs on the F:\ drive.
There was a need in my organization to upgrade to a new SAN. The Vendor assured us that all the files (.mdf, .ldf etc.) would be transferred safely and there would be no problems.
So the following steps were done:
1. During off hours, SQL Server Service(s) were stopped.
2. Data was copied from the H:\ drive of the Old SAN to the H:\ drive and same for the F:\ drive.
3. The services were started.
Everything came back up. The databases worked fine and all the DBCC CHECKDB did not report errors.
I ran rebuid indexes, sp_updatestats and other scripts. Everything is fine. The users do not see any problems.
However, I noticed that backups are taking 3 times as long. We used to back up the databases to the local drive (C:\ drive not SAN). However, the backups now take 3 times as long. I tried creating new Maitenance Job for the backup. But the same thing happens. Backupups (Which is really BACKUP DATABASE TO DISK=... command) is still taking 3 times as long.
All the settings on the new SAN have been checked and double checked. No issues there.
Why is this happening? Should I have detached the databases and re-attached the databases instead of moving files to a new SAN, after stopping services.
Thanks
- If the sqlserver instances have been stopped, everything is safe to copy.
Keep in mind, you need to make sure you copy everything, including authorities, ...
This seems to have been done very well by your migration team.
- I hope you did double check the san LUNs were defined the same as they were on your old san, or someone should have come up with very good performance reasons on why to change the LUN config !
You probably have a throughput issue if your backup is needing 3 times the time as before.
- Is your san bandwith the same or better than before ?
- are the san switches set up using the same or better settings than before.
They should have configured the LUNs in the same way as if you were configuring regular disks. (raid, blocksize, ...)
And please don't accept a "that's nolonger needed!" by any vendor ! Have them prove it on your system !!
At SSC there must be a couple of threads regarding SAN configuration and performance check. Have a look at them !
Contact your own SAN manager, in many cases his/her experience will be more valuable for your case than most (local) vendor representatives !
(We have had some very nice san issues, that were not supposed to have happened by the vendor(s) or were guaranteed not to be an issue, until we encountered them during microcode upgrade, san-switch redundancy elevation, ...)
Johan
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