I have a HP DL180 G6 with a P410 raid controller.

Presently this runs using 4x 1TB Samsung Spinpoint SATA drives, in a RAID10 configuration using default settings.

I am about to add a backplane to increase the drive capacity from 4 to 12 drives, and I plan to install 4 more 1TB SATA Drives.

  • The drives are matched and have close serial numbers (They arrived together in the Manufacturers pallet).
  • Model HD103UJ 1000GB/7200rpm/32M
  • Rated for 3GB/s

I will also be installing RHEL 6.1 x86_64.

My question is what would be the optimal RAID settings (stripe etc.) for this configuration?

To recap:

  • 8x Model HD103UJ 1000GB/7200rpm/32M
  • Rated for 3GB/s
  • RAID 10 configuration.

Thanks in advance.

Update for role:

  • Server is to become an iscsi target for an internal openstack deployment currently underway. (Glance)
  • Will also provide virtualisation through KVM
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    Your question is too vague...what are you doing with that server? Is it a DB server? Application server?... – Alex Nov 14 '11 at 16:34
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    Getting a bunch of drives from the same batch means they'll probably all have the same defects, meaning they're more likely to fail at the same time... – Chris S Nov 14 '11 at 16:44
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    Already a dead setup. even 8 such drives wont make it fast. I run a raid of 8xVelociraptors, 300gb each, 10k drives and I REGULARLY overlaod it - enoug hto get a 2nd level cache now that is SSD based. – TomTom Nov 14 '11 at 16:47
  • @ChrisS whilst it has been a long time since I read into RAID, it at least used to be the case that it was far better to have closely matched drives to ensure that parity was not adversely affected, and that ideally you should look for the "same batch" drives, though I do take your point. – Oneiroi Nov 14 '11 at 16:58
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    Well, it may not be helpfull but at the end a ford focus is not suitable to drive formula 1 races. Heavy virtualization needs heavy disc io - whether you like it or not. Your discs are slow end user side discs, large and not made for IO. Raid 10 is the b est you can make, but it is like a beefed up ford focus - still not suitable for the job. – TomTom Nov 14 '11 at 17:09

A few quick things...

Does the Smart Array P410 controller in your system have a battery-packed or flash-backed cache unit? If not, you will want to add one in order to have acceptable write performance (and possibly allow expansion of the drive array).

Are you doing this as a complete rebuild of the server, or are you looking to expand in-place?

I'd recommend RAID 1+0 in general, but especially with high-capacity low-speed drives. You can probably get by with the defaults suggested by the HP Array Configuration Utility.

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  • It is going to be a complete rebuild, I have already begun the process of migrating services off this system, I cam currently using 1+0 with default stripe, I am just unsure if that is the correct configuration. – Oneiroi Nov 14 '11 at 16:55
  • Yep, it's fine. Do you have the cache module and battery attached to the card? – ewwhite Nov 14 '11 at 16:58
  • it has 256MB cache module but I do not believe it has a battery module I will liase with our supplier about getting one, thanks. – Oneiroi Nov 14 '11 at 17:00

I always use RAID10 in iSCSI setup especially for virtualization.

To me it's the ideal balance between performance and reliability. And on top of it, it's much faster to rebuild a failed disk than in RAID 5 configuration. Especially with slowish 1TB drives.

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My default answer to any of these questions is always RAID 10, unless there's very special circumstances anyway. It's a great balance of performance and resilience, that said trying to get the best performance out of big slow consumer drives always strikes me as an odd choice - it's a bit like entering the Indy 500 in a tricked out Honda Civic, it'll start but will it end. Specifically I'd be worried that those disks have a 30% duty cycle, like every other cheapo 7.2k SATA, and driving them significantly over that will massively impact their MTBF, make sure you have at least two spares very close to hand. I'd also be a little worried about using non-HP disks with that controller but they're the choices you've made I guess.

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