Advertisement
If you have a new account but are having problems posting or verifying your account, please email us on hello@boards.ie for help. Thanks :)
Hello all! Please ensure that you are posting a new thread or question in the appropriate forum. The Feedback forum is overwhelmed with questions that are having to be moved elsewhere. If you need help to verify your account contact hello@boards.ie

Best RAID option for 5 drives?

Options
  • 24-04-2014 5:49pm
    #1
    Daniel S
    Registered Users Posts: 3,532 ✭✭✭


    Have 5 identical 80gb drives, what RAID option would you suggest for overall performance/reliability (apart from throwing them out and buying SSDs)? Stick 4 of them in RAID 0 and leave one extra? Or can 5 be run in RAID0? RAID5?


Comments

  • Options
    #2
    coylemj
    Registered Users Posts: 25,450 ✭✭✭✭coylemj


    For maximum capacity you could use RAID-5, without a hot spare you will get effectively 80% of the capacity as usable. With a hot spare you'd have 60% usable i.e. three data, one parity and one spare.

    RAID-0 would be madness - one disk goes and you're dead.

    For maximum performance and resilience you might consider RAID-0+1 (also know as RAID-10) which is striping and mirroring but with 5 disks you'd be using four disks with one hot spare so you'd only have the effective capacity of two drives or 40% of the total.

    Your choice - RAID-5 for max. usable capacity, RAID-10 for max. performance.


  • Options
    #3
    davo2001
    Registered Users Posts: 3,318 ✭✭✭davo2001


    RAID6? Double redundancy.


  • Options
    #4
    rovoagho
    Banned (with Prison Access) Posts: 1,151 ✭✭✭rovoagho


    RAID5 is dead. Unless you actually need the capacity right now, I'd be going for RAID10 with a hot spare.


  • Options
    #5
    Khannie
    Registered Users Posts: 37,485 ✭✭✭✭Khannie


    rovoagho wrote: »
    RAID5 is dead.

    What? I'm using it right now quite happily.


  • Options
    #6
    rovoagho
    Banned (with Prison Access) Posts: 1,151 ✭✭✭rovoagho


    If you're using small disks you should be fine, but anything above 1TB disks is recommended against these days. Rebuilds take too long and the risk of an additional failure in that time is too high. I can't post links now as I'm on mobile but googling for recent content on RAID5 should bring up some relevant commentary.


  • Advertisement
  • Options
    #7
    Gone Drinking
    Registered Users Posts: 2,809 ✭✭✭Gone Drinking


    Depends what you're looking for, RAID 6 if redundancy is what you need, RAID 10 if you're looking for performance.

    As the poster above said, its not recommended to use RAID 5 with SATA disks generally, especially if they're bigger than 1TB. Rebuilds take a long time and performance takes a decent knock during that period. SATA disks aren't reliable enough and working in the storage industry myself, have seen the horror stories of RAID 5 and SATA disks causing complete data loss on many occasions.

    Either way, back up your back ups :)


  • Options
    #8
    moc moc a moc
    Registered Users Posts: 1,299 ✭✭✭moc moc a moc


    Khannie wrote: »
    What? I'm using it right now quite happily.

    That's because you haven't been screwed by it yet...


  • Options
    #9
    coylemj
    Registered Users Posts: 25,450 ✭✭✭✭coylemj


    moc moc a moc wrote: »
    That's because you haven't been screwed by it yet...

    So what you're saying is that if we all hang around long enough, you'll eventually be proved right :rolleyes:


  • Options
    #10
    rovoagho
    Banned (with Prison Access) Posts: 1,151 ✭✭✭rovoagho


    They haven't, but I will: If you're using disks >1GB in size, it's only a matter of time before you have data loss. You should be planning to switch to another level in the medium term. If you need proof of our /insane/ assertions, have a Google for yourself. Start with "Dell RAID5" for their recommendation on the subject. Dell big enough for you?


  • Options
    #11
    coylemj
    Registered Users Posts: 25,450 ✭✭✭✭coylemj


    rovoagho wrote: »
    They haven't, but I will: If you're using disks >1GB in size, it's only a matter of time before you have data loss. You should be planning to switch to another level in the medium term. If you need proof of our /insane/ assertions, have a Google for yourself. Start with "Dell RAID5" for their recommendation on the subject. Dell big enough for you?

    Assuming you meant '>1TB' rather than one gigabyte and noting your earlier post...
    rovoagho wrote: »
    If you're using small disks you should be fine, but anything above 1TB disks is recommended against these days.

    Then can I suggest that you read the OP's first post - his drives are 80GB so your warnings about long rebuild times are not applicable.


  • Advertisement
  • Options
    #12
    rovoagho
    Banned (with Prison Access) Posts: 1,151 ✭✭✭rovoagho


    I wasn't talking to the OP in this case, I was talking to you, and it should be pretty obvious from the comment you quoted that it was a general warning about RAID5. Well done for picking up on my 1GB / 1TB typo though, I'm sure there were several incredibly stupid people that didn't notice it. Your pedantry is superb.


  • Options
    #13
    coylemj
    Registered Users Posts: 25,450 ✭✭✭✭coylemj


    rovoagho wrote: »
    Your pedantry is superb.

    This is a technology discussion, not a soccer forum. Lay off the aggressive put-downs.


  • Options
    #14
    Khannie
    Registered Users Posts: 37,485 ✭✭✭✭Khannie


    moc moc a moc wrote: »
    That's because you haven't been screwed by it yet...

    I've been using (Linux Kernel) software raid 5 for about 8 years now. Never been screwed by it. I acknowledge that failure during rebuild is a possibility. My drives are not > 1TB, though I do have access to shared network share that uses RAID5 with 2TB drives (currently 5 of them in RAID5).

    I'd be interested in what the rebuild time on an array of that size is.

    I wouldn't take Dell to mean too much tbh. Large corporations are going to all be about ass coverage.


  • Options
    #15
    Khannie
    Registered Users Posts: 37,485 ✭✭✭✭Khannie


    Khannie wrote: »
    I'd be interested in what the rebuild time on an array of that size is.

    Looks like probably in the 8 hour region, give or take.


  • Options
    #16
    BailMeOut
    Registered Users Posts: 2,985 ✭✭✭BailMeOut


    coylemj wrote: »
    For maximum performance and resilience you might consider RAID-0+1 (also know as RAID-10)

    Sorry to be pedantic but RAID 0+1 is not also known as RAID10. One is a 'stripe of mirrors' and the other is a 'mirror of stripes'. They are quite different!

    Are you creating the RAID in your OS or on do you have an array controller that will handle this? The latter always being the preferred choice.


  • Options
    #17
    Khannie
    Registered Users Posts: 37,485 ✭✭✭✭Khannie


    BailMeOut wrote: »
    Are you creating the RAID in your OS or on do you have an array controller that will handle this? The latter always being the preferred choice.

    Not at all. I would take the Linux kernel software RAID over hardware RAID any day in a home environment (and I have argued for it in a production environment). The reason is simple: It is hardware agnostic and the compute power required is now essentially nothing.

    RAID controller fails? Not to worry. You're not tied to it.


  • Options
    #18
    colm_c
    Registered Users Posts: 2,031 ✭✭✭colm_c


    Sorry for the thread hijack, but what's the current thinking on software like unraid (http://lime-technology.com/) for home servers?

    My current NAS is becoming slow and I'm going to build a new one at the end of the summer. At the moment it's down to either a linux RAID or Xen with unraid.

    For someone like me who wants to keep expanding their storage over time it just seems like a better option, and I can even mix and match drive sizes. And if one drive does fail the others are still accessible.


Advertisement