topic Re: How to segment drives in Disk Enclosures

How to segment drives

rad-air — Thu, 22 Dec 2005 15:51:50 GMT

Any suggestions how to segment drives in a Storageworks 4314 enclosure?
There are 12 equal sized spindles attached to a single bus enclosure, which is connected to a SA5304.
I think I will create 2 arrays with 6 disks on each, this will allow me to stay more flexibel on reconfiguration. Does it make sense, to have two ADG/Raid6 arrays? Only half the size of all disks is needed, so ADG or even RAID10 would be possible.
Is Raid6 better than Raid 5 with additional spare drive?
If creating 2 arrays, how to assign the drives to the array, drive 1-6 for Array A, and drive 7-12 to Array B? Or, for some reason, will it be better to assign drive 1,3,5,7,8,11 to Array A, and drive 2,4,6,8,10,12 to Array B?
Thanks for any recommandations.

Re: How to segment drives

Ivan Ferreira — Thu, 22 Dec 2005 16:25:24 GMT

Normally, an array is created and then the LUNs or logical drives.

With more disks in the array, the better the performance. So you can create one array and two logical drives with the desired protection level.

RAID ADG is a little better for availability for very worst for performance. RAID ADG can prevent data loss in the case of two "same timie" disk failure. RAID 5 with spare will may tolerate 2 disks failures in case that, one disk fails, and after the total reconstruction of the data to the spare, another disk fails.

RAID 5 writes only one parity information (that affects the performance), and RAID ADG writes 2 parity information (that affects the performance even more).