November 6, 2003 at 7:44 am
I have to make a new SQL2K clustered install, but my director wants to put a data files on a network attached drive on a SAN.
What down sides in the performance due to this install I could expect? And if there's a way at all to put the primary data files on the the other device? It's not a typical SQL scenario... What other dificulties I could encounter?
Thanks a lot.
MJ
November 6, 2003 at 8:05 am
I am not SAN expert but there is a trend to place database/files to SAN for better performance in storage subsystem. The SAN drivers have to be configured as local driver (Not Mapped) to the clustered servers and make them as disks resources to SQL Server before you can place database in them.
November 6, 2003 at 10:27 am
I'm new to SQL Administration.Could you, please, expalin the second part:how to "make them as disks resources to SQL Server"
Thanks a lot in advance.
November 6, 2003 at 11:32 am
SAN Drives are clusters of external drives usually hooked to the server via Fiber. Versus SCSI Attached external drive enclosers. But the concept is similiar.
They map a LUN (Logical Unit Numer on the SAN) or LUNs to the fiber card and each LUN should then look like a local drive to the server, and in fact acts like a local drive. The SAN handles the splitting across multiple drives for RAID, some buffering and other tasks as such.
So SQL sees them as just another drive. It doesn't know or care that they are not physically resident. SQL does not like DBs on mapped drives.
These LUNs can be split logically into multiple drives, although why you would I don't know.
One minor note, they must be defined to Windows as basic, not Dynamic disks. If you define them as Dynamic, they do come up properly after a reboot.
KlK, MCSE
KlK
November 6, 2003 at 11:37 am
It seems I have to work it out with my network guys.
Thanks a lot for all your help. You, guys, are great!
November 6, 2003 at 12:01 pm
Once you install Virtual SQL Server, It will create SQL Server cluster group. You need to add these SAN drivers as disks resources into SQL Server cluster group and configure SQL Server resource to depend on these disks resources before you can place database into them using tool called clustered administrator. Your network guys should know how to use this tool.
November 7, 2003 at 10:44 am
MJ, just wanted to clarify your setup, just because I think I see a conflict of terms in your original description. If you are putting the files on a SAN device, that is good; performance will be good since they are virtually local attached drives.
However you also said network attached drive, which implies NAS (Network Attached Storage, which is quite different. NAS is basically a headless file server, and performance will be poor because you are doing file access via slower network access. This will have slower performance for your database, and is not recommended.
Just making sure we do not have a misunderstanding of terminology, and trying to solve the wrong issue.
Edited by - mharr on 11/07/2003 10:45:47 AM
Edited by - mharr on 11/07/2003 10:46:16 AM
Mark
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