hardware RAID 5 vs. ZFS

Discussion in 'Storage' started by sowen, Jun 1, 2012.

  1. sowen New Member

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    sowen, Jun 1, 2012

    Hi all,
    I'm building a FreeNAS box to provide iSCSI targets for a few Windows servers. These targets will be my users main file storage.
    So far (during testing) it's working great.....
    However, I have a question regarding ZFS vs RAID5 setup.

    My server is an HP DL 380G5 with 32 gigs of RAM, and 8x500 gig SAS dual port 10k drives.

    I'm a bit "old school" and have set the drives up in 1 big RAID 5 array, managed by the internal HP RAID card.
    In this setup, if a drive fails, I simply replace it and the HP RAID card rebuilds the array in the background, and all is good.

    However, everything I read about ZFS, says to set the drives up in a JBOD configuration, and to let ZFS take over the drives.....

    I'm much more interested in using ZFS for it's snapshot and ZFS send functions (data backups) rather than trying to tweek it for speed.
    The system seem plenty fast as it sits.

    Opinions?
  2. Joshua Parker Ruehlig Well-Known Member

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    Joshua Parker Ruehlig, Jun 1, 2012

    I'm not saying zfs is slow but zfs isn't necessarily built for speed. though you can probably max your connection speed out with your 8x10k drives using zfs. It is built for data reliability, like you know your data is safe and bitrot hasn't screwed with it (which all other filesystems suffer), it also is a copy-on-write filesystem so power problems should cause any corruption.

    If you have the ability to try it, then maybe just set up a raidz2 with your drives (using jbob) and see if iscsi is still performing the same and what the transfer speed from ram to an iscsi drive. I wouldn't use the onboard raid personally with FreeNAS, if I'm gonna use FreeNAS I'd use zfs' ability to do stuff.
  3. sowen New Member

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    sowen, Jun 1, 2012

    Thanks Joshua,
    Looks like a moot point anyway....
    The HP has a p400 controller card, which has no ability for a JBOD setup (only raid levels 0, 0+1, 5 and 6).
    Look like 1 big-ol RAID 5 (or maybe 6?) array is in my future.
    To be honest...I was pretty much leaning that way anyway......I've used HP servers for a number of years and have a pretty warm/fuzzy high confidence feeling with regards to their RAID ability.
    now that I've said that......I'm sure that Mr. Murphy and his law are going to be knocking on my door soon......time to make sure my backups are working.. :) .

    Thanks again for your time and knowledge.
  4. Joshua Parker Ruehlig Well-Known Member

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    Joshua Parker Ruehlig, Jun 1, 2012

    Goodluck! I have no experience with hardware raid (all my stuff is cheap consumer crap).

    Just wondering, what happens is your card dies? Can you import the raid anywhere else, or do you need to buy another card?
  5. sowen New Member

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    sowen, Jun 1, 2012

    That's one option....

    More likely I would pop a few (different) drives into a second DL380 (I have 4...and I want to get a dedicated spare...), run the HP "SmartStart" utility, set the (different) drives up as RAID 5.
    Power off the server, remove the (different) drives, put in my 500 gig drives (in the exact same slot order in which they were removed), power the server on, and ta-da...they should pop right back up. No fuss no muss.
  6. paleoN Active Member

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    paleoN, Jun 1, 2012

    Have you searched for IT mode firmware to flash your controller with? You could also set them up as 8 single disk raid 0 arrays.

    See the first part of the NOTE in the hardware requirements. The TLER half won't apply as you have enterprise level drives.

    Do you have an idea of the iops you need? You may want to consider multiple vdevs.

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