DS4x00 hot spare?

[Stephan]

hi.

Let's say we have a ds4x00 with 3 EXPs. 3 with 146gb disks and the other with 300gb disks. What do you consider a 'best practice' when setting up your hot spare coverage? One per type of disks? One per enclosures?

Thanks.

 

[steinweo]

Hi Stephan,

I would recommend to setup one 300 GB as global hot spare. It would be a waste of space to setup more than one hot spare in your case. You do not have that much drives (3x 16 = 48 HDD's).

Here, I assume that 300 GB disk are FC (not SATA). When dealing with SATA disks , it a good practice to use RAID6 cause they are bigger and therefore reconstruction time is longer. Furthermore, MTBF is less for SATA than for FC.
So, it might be useful to setup a second hot spare too.

Regards, Olivier.

 

[Stephan]

Merci Olivier.

As a matter of fact, all drives are FC. So you would recommend 1x300gb, which would be available as a spare as well for the 146gb in case of failure right? I think the only restraint was that the spare drive has to be equal or bigger to the rest of the enclosure disks...?

Thanks again.

Stephan

 

[steinweo]

No problem. We're there to help each other. If I'm not wrong and IBM changed nothing to the way it works, the hot spare must be at least as big as the failing drive.

I must admit that I did not work with DS4000 for more than one year. In my new company (FSC), we are reselling CLARiiON from EMC.

Regards, Olivier.

 

[blackminder]

Merci Olivier.

As a matter of fact, all drives are FC. So you would recommend 1x300gb, which would be available as a spare as well for the 146gb in case of failure right? I think the only restraint was that the spare drive has to be equal or bigger to the rest of the enclosure disks...?

Thanks again.

Stephan

Hotspare must be equal or bigger than a failed drive. You can see hotspare coverage for 300 gb hotspare (in storage manager).
as for me, i setup 1x300gb hotspare and one 146 GB. 300 gb hotspare will cover 146gb and 300gb drives enclosures, 146gb hotspare will cover only 146 gb enclosures. i think its better than one hotspare.
on my storages i made one hotspare per enclosure.

 

[Stephan]

on my storages i made one hotspare per enclosure.

Hi Blackminder.

Yeah, in my other ds4700, we included a hotspare per enclosure, but i wanted to see everyone's opinion on that, as to maybe recuperate this space for something else if needed...
Thanks for the info as well.

Steph

 

[groener]

I have a DS4800 with 2 enclosures. One has 146GB FC drives the other 300GB FC drives. I have 1x300 hotspare and 1x146 hotspare. This way, the most important stuff on the 146's have double coverage, while the less important on the 300GB drawer has single coverage.

Maybe that's foolish and a waste of money. That's just what I decided.