SQL Server Disk Configuration

CoXeY

CoXeY

CoXeY

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Right thought i'd swing this one passed the hardware guru's around here...

I'm spec'ing out a SQL Server machine and would like to hear your thought's on optimal disk configuration.

The server itself is a Dell PowerEdge 2850 that can support a maximum of 6 SCSI drives. The idea is to centralise our various installations of SQL server onto a single central machine (all our egg's in one basket i know but that's why Acrnois TrueImage Enterpirise server will be used to back this baby up!).

To be honest i doubt very much that the load will ever near the capabilities of a single RAID 5 array but I want to make a point of setting this server up with optimum performance in mind.

So you've got six disks and up to three controllers to play with - how would you configure yours?


Dan.
 
Raid 5 with a hot spare, done in software if possible (I forget what Windows supports in that respect). CPU use would be negligable. Unless the load on the server becomes very large, you shouldn't even notice it. Doing RAID in software rather than hardware does solve the problem where when the RAID controller fails (it will) you don't automatically have to purchase the exact same brand and model of controller (you don't always, but RAID5 with a spare isn't always implemented in the same way by different controllers). It also takes some load off the RAID controller, meaning it *should* last longer.

Fair enough the load is then taken over by the CPU, but that shouldn't lower its life expectancy. At least, not in relation to the projected lifespan of the server.

**EDIT** If the RAID controller is on the motherboard, you want to take as much load away from it as possible. Replacement would be impossible.
 
Last edited:
StefanHolmes said:
Raid 5 with a hot spare, done in software if possible (I forget what Windows supports in that respect). CPU use would be negligable. Unless the load on the server becomes very large, you shouldn't even notice it. Doing RAID in software rather than hardware does solve the problem where when the RAID controller fails (it will) you don't automatically have to purchase the exact same brand and model of controller (you don't always, but RAID5 with a spare isn't always implemented in the same way by different controllers). It also takes some load off the RAID controller, meaning it *should* last longer.

Fair enough the load is then taken over by the CPU, but that shouldn't lower its life expectancy. At least, not in relation to the projected lifespan of the server.

**EDIT** If the RAID controller is on the motherboard, you want to take as much load away from it as possible. Replacement would be impossible.
Click to expand...

I've got about 200 servers under my control and I can't say that I've ever had a RAID controller die.

Doing RAID, especially level 5 in software is a bad idea, you'll waste CPU cycles that could be better put to use keeping your DB performance up.
 
The controller does not seem to support 0+1 but 1+0 (or 10) instead, after looking around this does not seem to be too much of problem but can guys point out the downsides of going with the latter?

Currently i'm thinking RAID1 for O/S, applications and transactions (on seperate partitions). Then RAID10 for the database files and tempdb. Sound about right?
 
Burbleflop said:
I've got about 200 servers under my control and I can't say that I've ever had a RAID controller die.

Doing RAID, especially level 5 in software is a bad idea, you'll waste CPU cycles that could be better put to use keeping your DB performance up.
Click to expand...
The other day one of our hosting servers running RAID 10 had its controller go **** up and bugger the whole shebang :( To be fair, it looks like there was also one faulty disk.

I agreee software RAID is silly here...hardware controllers exist for a reason, and it ain't difficult to keep spares like you should with disk.

If you need maximum performance then I'd go for 0+1, but if you need more reliability then I'd go for RAID10.
 
I dont like software RAID period - with storage controllers and hardware so cheap these days I dont see how anyone can justify it.

And to the OP, depends what applications are running on top of it. I have a couple of 2850's that have RAID-1 for the OS/Logs and RAID-10 for the database file - but the servers are mostly used for reporting with little transactional data, so having a lot of memory means it doesnt really rely on either. If you're going to be making a large amount of transactions then your log partition will need to be up to it.

For database installations, avoid RAID-5 like the plague.
 
As above we asked the software people as a server needs upgrading and as stated 6 disks, hardware raid mirrored OS and raid 10 for data.
 
Beansprout said:
The other day one of our hosting servers running RAID 10 had its controller go **** up and bugger the whole shebang :( To be fair, it looks like there was also one faulty disk.

I agreee software RAID is silly here...hardware controllers exist for a reason, and it ain't difficult to keep spares like you should with disk.

If you need maximum performance then I'd go for 0+1, but if you need more reliability then I'd go for RAID10.
Click to expand...

I agree we juse 0+1 on our MS SQL server at the moment

Stelly
 
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