Which RAID/LVM configuration for new 2x8TB file server is safest?

user1169420 asked:

I just built a totally new PC to be a fileserver. It has one 60gb SSD for OS (ubuntu 12.04), and 8 2tb data drives in it. I am looking for the safest, most stable way to set up a single giant storage pool with redundancy.

Considerations:

  • My TOP priority is protection of the data. Availability, reliability, resiliency, recoverability, and risk management. All of those words which mean not losing my files.
  • I’m not merely concerned with the theoretical risks implied by the
    nature of the raid types, but also practical considerations of
    simplicity, and minimum points of failure. Especially considering I
    am not an expert in RAID or FS technology and my ability to
    troubleshoot is limited to what I can google up.
  • This is not a write-heavy, like
    database servers with transactions day, it’s mainly to hold media for
    various streaming, as well as all of my users files for network access.
  • My worst nightmare is to find that due to some chaos-theory alpha
    particle shot out of the sun landing in a capacitor, to have some error in my
    HDDs/metadata/motherboard/software/whatever that renders the entire
    array unrecoverable. DOOM&H8!
  • Because I will be streaming data, read speed advantages are
    appreciated (but secondary)
  • Eventually I might want to add drives, with LVM pooling RAID1 pairs,
    this is easy. Would RAID6 or RAID10 arrays have to be rebuilt from
    scratch with blank drives?
  • If this is relevant, I have my 8 drives plugged into the 8 onboard
    SATA slots on my ASRock Z77 Extreme4 motherboard, 4 of which are
    SATA2 and 4 are SATA3. The OS is on a SSD hooked to a PCIe SATA
    controller. 8gb of RAM.
  • See #1 – My TOP priority is protection of the data.

I have read that RAID6 is actually less risky since any 2 disks can fail instead of only one per mirror-pair, and the main drawback of RAID6 is write speed, which I am not to concerned about. I have accepted the loss of half my drives to mirroring, so I dont want to sound greedy for even considering RAID6, but if its actually SAFER, faster for reads, AND lets me keep 12 gb instead of just 8, maybe it would be stupid not to. Or maybe I am missing a bigger picture

I guess what I am asking for is the drawbacks of, or which one is best suited for data protection, and to a lesser extent read speed, in an 8-12 drive array.

  • LVM(4x2tb) + nightly cronjob backups of independant disks
  • LVM(4xRAID1)
  • (RAID10)
  • (RAID6)

Thanks for your help!

My answer:


If you’re going to go the RAID 6 route, then do yourself a favor: Visit eBay and pick up a couple of PERC 6/i cards (one as a spare) and two SFF-8484 to 4xSFF-8482 cables to hook up the drives. You’ll thank me later.

If you decide to go with ZFS, then go whole hog and set up NexentaStor. That’s probably about the safest you’ll get with your data in its intended, uh, home.

And think very carefully about a backup strategy; neither RAID nor ZFS are backup. Backup of terabytes of data is not easy or cheap; it’s not usually something you can do over the Internet, and terabytes of “cloud” storage would set you back a lot more than the drives anyway.


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