Re: p812 controller - JBOD mode? (866 Views)
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Visitor
shane907
Posts: 3
Registered: ‎07-30-2013
Message 1 of 7 (1,006 Views)

p812 controller - JBOD mode?

Hello,

 

Is there any way to put a p812 controller into JBOD mode? We want to use software RAID with a large number of disks. So far I haven't found a way to allow the OS to see indivudal drives that aren't part of a RAID volume on the p812.

 

Thanks,

Shane

Visitor
RobertCElliott
Posts: 3
Registered: ‎07-30-2013
Message 2 of 7 (997 Views)

Re: p812 controller - JBOD mode?

Not in a ProLiant system (HP-UX is different).  

 

Instead, you can create a set of RAID-0 logical drives each containing a single physical drive.  Smart Array controller will still provide the non-volatile write cache to speed up writes, manage SMART warnings, control the drive LEDs, etc.

 

 

Honored Contributor
Johan Guldmyr
Posts: 3,848
Registered: ‎06-14-2009
Message 3 of 7 (989 Views)

Re: p812 controller - JBOD mode?

Hi,

It's possible to use smartctl/smartd for on disks that are behind a smart array controller. But perhaps you're doing this for another reason? ZFS? Perhaps you want to try first if you get better performance with many RAID0 or if it's actually better with less arrays. It's certainly easier to manage with less arrays.

Another question I'd have: how many arrays can you create on a P812? I couldn't find it in the quickspecs, only that it maxed out at 108 disks. Can it also do 108 arrays and 108 logical drives?
Visitor
shane907
Posts: 3
Registered: ‎07-30-2013
Message 4 of 7 (985 Views)

Re: p812 controller - JBOD mode?

Thanks very much for the replies so far.

 

We have a few DL380 servers that connect to MDS600 disk systems via P812 controllers. We're aiming to manage the raid arrays using software raid (mdadm) to allow for specific options (RAID 10 far 2), ease of monitoring using standard linux tools, and survivability of hardware failure (as software raid should be able to be reassembled using different hardware if needed).

 

Setting up every drive as a RAID 0 volume is an option as long as there's no performance penalty (and Robert's post indicates that there would actually be benefits), but this would be cumbersome to manage considering that each MDS600 would hold 70 drives to be manually set up as individual RAID 0 volumes (multiplied by four server/disk system pairs).

 

Barring any new information we'll test performance on both hardware RAID 10 and software RAID 10 far 2 over hardware RAID 0 and evaluate from there. I just wanted to make sure we weren't missing an option to allow the OS pass-through access to drives not in a hardware raid volume.

 

Thanks,

Shane

Visitor
RobertCElliott
Posts: 3
Registered: ‎07-30-2013
Message 5 of 7 (969 Views)

Re: p812 controller - JBOD mode?

That controller is limited to 64 logical drives, so won't quite support 1:1 mapping of an MDS600 filled with 70 drives. 

 

Although it'd be awkward to manage a large number of logical drives with the ACU GUI, the command-line version shouldn't be too bad (invoke from a shell script or perl script).

 

 

Visitor
shane907
Posts: 3
Registered: ‎07-30-2013
Message 6 of 7 (961 Views)

Re: p812 controller - JBOD mode?

Thanks Robert, that hpacucli tool was exactly what I was looking for. Writing a batch script to create RAID0 volumes for all unassigned drives on a controller was easy.

 

If anyone's interested, with an eight drive test we're not seeing any significant differences in read and write tests between software RAID10/hardware RAID0 and hardware RAID 1+0, although hdparm reports that the software/hardware hybrid has somewhat faster buffered disk reads.

 

The HP product info page on the p812 [1] states that it supports up to 108 drives...hopefully that's the case, as that's why we purchased them.

 

Thanks again,

Shane

 

[1] http://h18000.www1.hp.com/products/servers/proliantstorage/arraycontrollers/smartarrayp812/

Regular Advisor
David_Tocker
Posts: 100
Registered: ‎05-14-2012
Message 7 of 7 (866 Views)

Re: p812 controller - JBOD mode?

For future reference - buying a p812 and using it for jbod is like using a ducati motorcycle for a generator. It is both wasteful and inefficient. For zfs etc  you are going to get better performance and reliability using one of the recommended cards (LSI is common) that are designed to run in a straight through/hba type mode.

Regards.

David Tocker
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