Re: 20 drives, raid 5 with hot spare, puts two drives in hot spare

Either of the two controllers can control the RAID set but only one of them 'owns' it at any moment.

Because there are two paths to all SAS disks BOTH controllers have a dedicated path to each disk so yes you will see all 20 drives under each of the two RAID cards. In fact one of the failures I have seen is where a drive loses a path and thus only one RAID card could communicate with it. In this case a drive replacement is required as you would expect. You can see this in work with disk units, display path status.

As for the hot spares I'm not sure why with only one RAID set it allocated two in your case. I would have expected it to create two RAID sets of 9 each with a hot spare. In theory this would have provided better throughput as each controller now is handling 9 drives while the current configuration has one controller cooling it's heels while the other does all the work.

Of course the degree of additional performance may be insignificant and without testing, I suppose it's more of a hunch than a fact.

Are your RAID controllers set for Performance, Capacity, or Balanced?

- Larry "DrFranken" Bolhuis

www.frankeni.com
www.iDevCloud.com
www.iInTheCloud.com

On 4/28/2014 11:16 AM, rob@xxxxxxxxx wrote:

So, this raid set is owned by two controllers? And each of those
controllers has a hot spare?

WRKHDWRSC *STG
Resource Type-model Status Text
CMB02 xxxx-001 Operational Storage Controller
DC02 xxxx-001 Operational Storage Controller
...
CMB11 xxxx-001 Operational Storage Controller
DC05 xxxx-001 Operational Storage Controller

and using "9=Work with resource"
shows two "Device Services" and all 20 drives for each of these two
Storage Controllers. Option 7 shows one storage controller in one slot
and one in another.

So, if I would have set it up with two raid sets I would still only use
two hot spares. One for each controller.


Rob Berendt