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P4500G2 -- Mixing Hard Disks

P4500G2 -- Mixing Hard Disks

Hello,

 

We have the following 2 units:

 

1) P4500 G2 with 12 x 450GB 15k SAS

2) P4500 G2 with 12 x 1TB 7.2k SATA MDL

 

I would like to know if I can split the hard disks, so each one of the unit can have 6 x 450GB SAS in bays 1-6 and 6 x 1TB SATA in bays 7-12. I want to have 2 different RAID10 arrays in each unit, each one of the arrays to be under network raid with the appropriate array on the other node.

 

My question is: Has anyone ever done this? Are there any known problems in mixing different hard disks in the same controller but *not* in the same raid array?

 

Sincerely,

George Vardikos

 

3 REPLIES
Sbrown
Valued Contributor

Re: P4500G2 -- Mixing Hard Disks

I cannot confirm this is true for the P4500 G2 but for many servers placing SATA drives on the same physical as SAS would force the SAS drives to drop their LVD voltage to levels that are safe to use with SATA which hypothetically could lower signal integrity of the SAS drives.

The MSA line used an interposer to present the SATA drives as SAS to prevent this.

I have done this in an HP server and the only oddity was when a catastrophic failure happened and we re-inserted a drive, another drive failed (no reason). One was SAS , One was SATA.

Honestly best to talk to support on this one, as they are ones who decide to support it or not. Or use the VSA , where you can mix up any brew you want.
a_o
Valued Contributor

Re: P4500G2 -- Mixing Hard Disks

Apart from the physical (LVD voltages), this would be problematic from a SAN I/Q performance perspective.

With LH/Storevirtual, each node (NSM) gets formatted by default as a single config array and a single data RAID array.

Even if you were to create multiple data arrays, the LUNs you create will be written across both arrays, as the storage is presented as one contiguous volume to SAN I/Q.
So you'll be limiting the performance to the lowest common denominator - i.e. 7.2K SATA.

AFAIK, Sub-LUN tiering is only available in VSA V11 not on NSMs.

If you don't do what you're thinking of and leave them as they are - putting both units in the same cluster will be sub-optimal. Your Network RAID performance will be gated by the same 7.k SATA.

Your best bet is to have matching units, i.e. buy additional P4500 G2 15k SAS, plus another P4500 G2 with 7.2k SATA. This way, you'll have 2 clusters - each with matching NSMs.

Sbrown
Valued Contributor

Re: P4500G2 -- Mixing Hard Disks

You know what would be a good feature - Allow folks to migrate between VSA and Physical licenses.

Veeam has this - you can migrate your licenses between hyper-v and esxi as much as you want.

With VSA11 you could run two vsa on one physical machine (assuming you have enough licensing).

I didn't realize storevirtual 2014 did not have Adaptive Optimization for the physicals.