Which disks on RAID 50 are in the same RAID set?

Question

I am curious to know which disks are in a RAID set together on a PS6500E with a RAID 50 configuration. From what I can piece together from documentation it looks like there are likely 7 RAID 5 sets within a standard 48 disk RAID 50 configuration with 2 of those as hot spares. This is based on a doc that says 46 disks are used in a RAID 50 configuration for data/parity with a raw capacity equivalent to 39 disks. That would mean the equivalent of 7 disks are used for parity, which would mean 7 separate RAID 5 sets (obviously not all of equal size). Unless you loose 2 disks in a single set you are good. The problem we recently had is that we had disk 36 fail and 12.5 hours into the reconstruction of the failed drive from a hot spare, disk 36 went dead. This took the whole member offline, so I am assuming these two disks were in the same RAID set. I know that information does not appear to be viewable from within the Group Manager or SanHQ, so is it viewable somewhere from a SSH command maybe? I know that with hot spares moving around when you have failed drives, it is quite possible that the RAID set member disks could be all over the place. Would be nice to know the layout at any given time. That info has to be known by them member, so it would just be an issue of how to view it.

Christian Hanse · Answer

First.

** WARNING THIS IS HIGHLY UNSUPPORTED **

The tool your looking for is raidtool.

Here is a blog, that describes how to access it.

integritycomm.blogspot.com/.../equallogic-cli-undocumented-commands.html

DonDallas71 · Answer

The raidtool helps a little bit, although it don't think it is telling the whole story. I am thinking that within each 14 drive LUN there are likely two RAID sets (except the 4 drive LUN). The reason I think this is that on a PS6000 it only shows a single LUN and I am certain, based on the "CHOOSING A MEMBER RAID POLICY" doc page 8, that there are 2 RAID sets.

From a PS6500

RAID LUN 0 Ok.

14 Drives (14,15,16,17,18,19,20,21,22,23,24,25,26,27)

RAID 50 (64KB sectPerSU)

Capacity 11,942,405,603,328 bytes

RAID LUN 1 Faulted Beyond Recovery.

14 Drives (28,29,30,31,32,33,34,35,?,37,38,39,40,47r)

RAID 50 (64KB sectPerSU)

Capacity 11,942,405,603,328 bytes

RAID LUN 2 Ok.

04 Drives (42,43,44,45)

RAID 5 (64KB sectPerSU)

Capacity 2,985,601,400,832 bytes

RAID LUN 3 Ok.

14 Drives (0,2,4,6,8,1,3,5,7,9,10,11,12,13)

RAID 50 (64KB sectPerSU)

Capacity 11,942,405,603,328 bytes

Available Drives List: 41,46

From a PS6000

Driver Status: Ok

RAID LUN 0 Ok.

14 Drives (0,2,4,6,8,15,12,1,3,5,7,9,11,13)

RAID 50 (64KB sectPerSU)

Capacity 5,185,085,374,464 bytes

Available Drives List: 10,14

FluidFS

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