XP24K and SQL server 2005

[John Town]

Hi,

I would like to know what is the Stripe Unit Size that the XP24k array uses and what is Partition Starting Offset recommended for MS sql server 2005. Or if anyone knows if a guideline manual is available with this information.

Thanks

JT

[IBaltay]

Hi,
this could be aplied also for the sql 2005...
http://h20195.www2.hp.com/V2/GetPDF.aspx/4AA2-5263ENW.pdf
â ¢ Allocation Unit Size 64K
â ¢ Alignment set to 1024 (default)

[Nigel Poulton · Accepted solution]

John,

The previous comment might be misleading. Stripe size on the XP is not 64K.

Stripe size on the XP depends on the RAID configuration chosen. Below is the stripe size based on every RAID configuration supported on the XP -

RAID10 2+2 = 1024K
RAID10 4+4 = 2048K
RAID5 3+1 = 1536K
RAID5 7+1 = 3584K
RAID5 6+2 = 3072K
RAID5 14+2 = 7168K
RAID5 28+4 = 14336K

If you care, below is some more technical information -

The formula for working out stripe size for all RAID configurations on the XP is -

(256 * x) * y

Where x is always 2 (because the XP always writes 2 tracks at a time, and track size for OPEN-V volumes is 256K ) and y is the number of data spindles in the RAID set. So the formula for working out stripe size on RAID5(7+1) is as follows -

(256 * 2) * 7 = 3584K

To be clear, the above is based onusing the SNIA definition of â stripe sizeâ â

â A parity RAID array's stripe size is the stripe depth multiplied by the number of member extents less the number of parity extentsâ

You can check out the following that I have written on the subject -

In depth info on RAID10 (4+4) on the XP12K and XP24K -
http://blogs.rupturedmonkey.com/?p=211

In depth info on stripe sizes on the XP -
http://blogs.rupturedmonkey.com/?p=182

An unofficial User Manual for the XP explaining hardware and cache operations etc. Much better than what Hitachi and HP provide -
http://blogs.rupturedmonkey.com/?p=356

HTH - Nigel

[John Town]

Very good info. Just what I needed. Thanks to both.

[John Town]

Worked for me. Thanks again.