RAID 5+1 ??

[DHR]

Evening all, hoping you could provide me with some pointers. I've come accross a MSSQL 2000 database suffering from read performance issues, writes spike now and again but are generally okay. The thing thats puzzled me is the disk configuration is RAID 5+1 (or 51!) i've never seen that sort of setup before.

I'm aware that there are issues with badly written TSQL throughout the db which are causing some of the read issue but i can't help but think that the disks would be better configured using RAID 5 for the data and 0+1 for logs opposed to using just this one 5+1 configuration.

I'd assume as with RAID 5 that reading data wouldn't be an issue with RAID 5+1? Or am i wrong? Is there that bigger overhead to cause these read issues?

(edit - i'm going to be on msn most of the night so if you fancy a chat about it i'd be more than happy to!!!! - see my profile for msn addy)

 

[rpstewart]

Yikes, RAID51! That's not something you see everyday.

I doubt that your read performance will be hindered by the array so you're right in pointing the finger at the SQL. I'm not a SQL Server expert (DB2's my poison) but I'd check the usual suspects - are all the joins indexed, are the database stats up to date etc. It's also worth looking to see what the ratio of physical to logical I/O is and seeing if it's worth chucking more RAM at whatever the SQL Server equivalents of bufferpools are.

Whether you'd benefit from redoing the storage is going to depend on the workload mix on the server. If it's query based with only occasional writes then you might not see a lot of benefit but if it's a mixed load then definitely get the logs off onto a separate disk/array