Have just the one storage bay right now (SAS 15K 600GB x 6) and have configured one storage pool in RAID 10 with 4 disks (and two global spares). For each blade, I've created a volume and mapped accordingly:

  • Blade #1 400 GB
  • Blade #2 200 GB
  • Blade #3 100 GB
  • Blade #4 100 GB

When I boot up Blade 1 and enter into the UEFI Setup (F1) followed by the Adapters and UEFI Drivers > LSI Logic Fusion MPT SAS Driver Utility, I see 4 disks: two are the on-board 73GB drives, the other two are 200GB each and assume I'm being presented with two logical disks from the volume I created and mapped to this blade. I was a bit surprised by this: I figured I would've been presented with one logical drive per volume, not two.

I'm assuming I can just configure whatever RAID level I wish that supports two disks, but not really sure what the benefits/trade-offs here. Should I go with RAID 10 on top of RAID 10? RAID 0? Software RAID 0/1/10? Does it even matter?

If this is "normal" to see two disks, then I'm going to likely just do some benchmarking and see if it makes a difference changing the RAID levels (my guess is no); if this is not normal, well, please let me know. :)


The fog has lifted...

I was not seeing a 50/50 split between both disks; I was seeing your typical multipathing problem that was resolved by setting up the proper multipathing configuration in the host OS. Also had to unmap the volume, reinstall Ubuntu on the onboard RAID array first, then re-map, install/run multipath-tools (with the multipath.conf I grabbed from IBM's site).

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