XP12000 configuration?

[Scott Heisey]

Need help in determining configuration for the XP12000.

1. What does 2D+2D or 4D+4D mean for RAID 1? Is this the maximum number of disks in RAID 1 configuration.
2. This leads me to the next question. How many disks can I have in RAID 1 configuration?
3. If I don’t want to use host based Stripping and I am not using Autoluns. What is the best way get the best stripping at the hardware level.
4. Can I set the stripe size at the hardware level or is it fixed.

[Sameer_Nirmal]

Hi Scott,

Refer the attached document for your questions on RAID 1.

You would get better performance with host based striping. In XP Arrays, array in-built hardware striping works within a array group. With host based striping, you can do striping across the array groups on the top of the AG hardware striping.

I am not sure about the default h/w stripe size on XP12K. I guess it is fixed.

[Alzhy]

1. What does 2D+2D or 4D+4D mean for RAID 1? Is this the maximum number of disks in RAID 1 configuration.

They mean mirrored configuration and also indicates how many physical disks are involved in the "array group" -- from which ldevs/luns are carved and presented to the server.

2. This leads me to the next question. How many disks can I have in RAID 1 configuration?

Answered above. Either 4 or 8.

3. If I dont want to use host based Stripping and I am not using Autoluns. What is the best way get the best stripping at the hardware level.

You have no choice but to do another level of striping on the host level to get the most out of any XP or HItachi array architecture. Your stripe should be accross LUNS from different array groups and "ACPs".

Note that regardless of how your array groups are set up (mirror or parity) - on the host level - you still stripe them specially if they will be destined for database use.


4. Can I set the stripe size at the hardware level or is it fixed.

No. The Array Groups are not customer configurable. When you buy a set of 4 or 8 disks that will become an "array group" -- you instruct HP or HItachi to carved it into mirror groups (2D+2D or 4D+4D) or parity groups (3+1P, 7+1P or 6+2D).

[Nigel Poulton]

According to a Hitachi document that I have (HP XP range of storage is actually HITACHI storage) the stripe size for the xp1024 is 24 tracks and is not configurable.
Obviously the size may have changed for the xp12000.
But I can confirm that the stripe size is not configurable on the XP12000 either.