topic Re: Optimal Disk Configuration in Disk Enclosures

Optimal Disk Configuration

Andrew Davenport — Thu, 11 May 2006 07:24:44 GMT

Hi all, performance question here.

The MSA30 is attached via a 6402 controller and contains 14 x 72.8GB drives.
The server will be running SQL 2000 on Windows 2003 R2.
As far as the disks are concerned I am being asked to configure all the drives in the MSA30 as 7, 2 disk mirrors and make each logical drive 72.8GB. Each mirrored pair will have 1 partition created on it.
The justification for this is that it would allow maximum performance for the log file partition and the various data and DB partitions.
In my understanding this would not be as good as making 1, 0+1 array across all disks and then partitioning the logical drive down in the O/S.
My argument is that each read and write operation will have at least 7 heads to choose from. And therefore boost performance.
Maybe I am wrong, could someone shed some light?

Re: Optimal Disk Configuration

Jefferson Humber — Thu, 11 May 2006 07:38:03 GMT

Andrew,

You are right performance will be better with the data striped across more mirrored pairs, and then logically divided into LUN's on the O/S.

This is kinda how the EVA array controllers do it, by creating a disk group (array) and creating LUN's within it.

The only question really is do you want to keep the DB & Logfiles / Redo logs on the same array ?

Re: Optimal Disk Configuration

Andrew Davenport — Thu, 11 May 2006 08:04:51 GMT

As far as i can see we have to keep the log files on the same array or at least the same controller and scsi channels.
The best i can do it break out the log files logical disks and put them in their own array but due to budget constraints i dont have any spare drives to play with.
This is what we have and the solution we are working with is called SAP

DL380 G4 Server Internal
2 x 72.8GB 0+1 (16GB O/S, remainder is static data)
2 x 72.8GB 0+1 4.1GB Swap, 4.1GB Swap, 2.1GB Swap remainder wasted. This allows a 10GB Swap file required by SAP.
2 x 72.8GB 0+1 Executable SAP Files

MSA 30
14 x 72.8GB
They has asked that i make 2 x 72.8 0+1 for logs, 2 x 72.8 0+1 for TempDB.
Then they need Data drives 1 through 5.
I have made this on 0+1 array and partitioned it in the O/S
They were asking for each one to be a seperate mirror which i think is a terrible idea.

If you can think of a better config let me know.