February 27, 2008 at 7:45 am
Hello all,
I recently been placed on a project to work with the storage guys to help move SQL Servers from one SAN system to another. They are replacing our current SAN environment. Does anyone have any experience in this? I'm trying to find out if there is anything I need to watch out for in terms of transferring the data from one SAN system to another.
February 27, 2008 at 9:50 pm
Depends on the migration strategy, SQL Server needs to be stopped and restarted at some checkpoints (before/after data transfer).
Set SQL Server services Start Mode to manual instead of auto during the data transfer stage. The host/server may have a couple of OS restarts for SAN migration. SQL Server no need to be up that time.
Always have a backup.
March 1, 2008 at 9:31 am
The complexity depends on the scope of the work.
Last summer, we migrated our EMC DMX 1000 to a DMX3 system and at the same time moved to new fiber switches. Our EMC Clariion CX700 system was unchanged as well as our Sentara systems. We also improved some of our fiber cabling in the process (installed Fiber patch panels to replace direct cable runs)
We were able to connect to both the new SAN disks and the old SAN disks at the same time. However, due to some fiber network limitations, we had to move all servers connected to the Clariion to the new switches at the same time (which required all work to be done simultaneously).
If I were to do it again, I would recommend separating the fiber switch replacement from the migrations. Had we done so, we could have moved systems gradually (or at least not had to move data at the same time we were changing switches, reducing the length of the time where all systems had to be down).
I also would have planned downtimes in advance of the move to get the Fiber Channel driver, Fiber Channel Firmware, and Powerpath Software (EMC Fiber Channel Load Balancing / path management software) completed before the migration. EMC always wants the current versions installed when doing stuff like this, but keeping the current version is difficult when there seems to be a new version every month (and you normally only get to work on your systems once a month).
If you can see both your new SAN disks and your old SAN disks at the same time, migration is MUCH easier.
Once you see the new disks, prepare, format, and assign drive letters.
At the migration time, you stop SQL and services that depend on it (to release open file locks) and copy files from old drive to new drive, maintaining folder structure. Once the copy is complete, you change the drive letters on the volume and restart. Just make sure if you have any hidden or system files (SQL doesn't create any of these), that whatever method of copying files picks up all the files.
When we were discussing this with EMC, they wanted to license a program called Open Migrator that would mirror your old SAN disks to your new SAN disks while the system was in use, so your cutover would be limited. Unfortunately, the program required at least 2 reboots to install, our software vendors didn't approve its use, and copying the files took about the same time as required to shutdown the system install the software and an additional shutdown to uninstall the software.
If the only thing you have on your SAN volumes is SQL Databases, they move fairly quickly. We had a couple systems that had LOTS of small files that don't move fast no matter what you do.
Do lots of planning to make it go smoother. Remember how you did things and what could have been improved, since you WILL have to do this again (EMC likes to have you ugrade every three years).
Viewing 3 posts - 1 through 2 (of 2 total)
You must be logged in to reply to this topic. Login to reply