Zfs pool adding extra drives

Discussion in 'Storage' started by Smashmouthftball, Feb 3, 2013.

  1. Smashmouthftball New Member

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    Smashmouthftball, Feb 3, 2013

    Hi everyone, this is my first post ever and my first time building a freenas system, so I am very scared/excited! Also I have a couple of questions:

    I am theming to build something that is similar to a drobo but running on freenas...right now my computer has enough bays and sata ports (on board and via sata card) to power 8 drives. However I only have 5 drives.

    Now doing my research I read that drives cannot be added (the physical number is set when the zpool is created) but the drives themselves can be removed and replaced with larger drives to increase capacity.

    Is there any truth to this? Can I potentially create a zpool with empty slots for drives anticipating adding new drives in the future? And is the process plug and play or does it require some sort of configuration?

    Very grateful for the help front you guys, thanks again.
  2. cyberjock Forum Guard Dog/Admin

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    cyberjock, Feb 3, 2013

    You should read the stickies in the Noob section... I've answered that question there.
  3. Smashmouthftball New Member

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    Smashmouthftball, Feb 3, 2013

    alright myabe i should just buy a drobo...its odd that someone hasnt created a software solution to allow for drive upgrades and replacement as needed...
  4. cyberjock Forum Guard Dog/Admin

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    cyberjock, Feb 3, 2013

    Drobo's design is for a totally different customer base than FreeNAS. Drobos don't have ZFS nor the reliability that can come from a properly setup FreeNAS server. They're great for cheap server space and low performance/reliability compared to FreeNAS.
  5. zicoz New Member

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    zicoz, Feb 4, 2013

    You could create one Vdev with 4 drives now, and then create another Vdev with 4 drives later and that way expand your available storage. It's all in the guide.
  6. fracai Member

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    fracai, Feb 4, 2013

    Or create your 4 drive VDEV and then, one-by-one, replace the drives with larger versions.

    There's also a tutorial I've seen on manually partitioning each drive and building VDEVs from the partitions. Search online for "ZFS Drobo". This is the one that started me: http://forums.smallnetbuilder.com/showthread.php?t=5599

    It always seemed like too much work, not enough benefit, and likely to be constricting later on.
  7. survive Super Moderator

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    survive, Feb 4, 2013

    Hi Smashmouthftball,

    Do a little research into the history of ZFS and you should get a better understanding about why this add-drives-to-a-pool thing exists. Basically ZFS is a big, beefy filesystem that started out in the enterprise where you just don't add drives one by one, you add them by the disk shelf or rack of disk shelves.

    It's a common concern for the user who wants to grow their storage drive by drive, but it is something that can be worked around given proper education and planning.

    -Will
  8. joeschmuck Old Man

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    joeschmuck, Feb 4, 2013

    Or you could create another zpool vice adding another vdev (group of drives) into the same zpool. I rarely hear this option being offered up as a solution, maybe because there needs to be some understanding along with it as to the benefits and limitations.
  9. cyberjock Forum Guard Dog/Admin

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    cyberjock, Feb 4, 2013

    I think the main reason it's not offered up as a solution is that the people asking the question are usually noobs, so why give them answers that add even more complexity to their woes. It's like if my mom asks how to have her own webpage, I wouldn't tell her to make her own http server etc etc. I'd tell her to call one of those web hosting services that does most of the hard work for you and you just upload some html files.

    The answer is tailored to the person asking the question. Ergo, if you are asking the forum how to add 1 more disk to your vdev you definitely do not have a very firm grasp of the fundamentals. The last thing I'd try to tell them to do is make another vdev. I'd tell them to go read the manual or my guide on vdevs and let them understand why they can't do what they want and let them decide how to proceed.
  10. fracai Member

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    fracai, Feb 5, 2013

    I think one reason it isn't offered is that it just doesn't occur to the responder as an option. Certainly one of the benefits of ZFS is that you can throw a bunch of disks at it and treat them as one volume. Even if you create multiple datasets, they can grow independently and be resized without the constraits of repartitioning. Managing multiple pools is a way to increase the array size, but it also defeats some of the benefits. Further, if you're only adding the one drive (as most users are asking about), you're still not keeping the redundancy that made ZFS seem so shiny.

    So it is an option that should be offered, but it's another set of benefits and constraints that need to be considered as well.
  11. Smashmouthftball New Member

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    Smashmouthftball, Feb 6, 2013

    Wow I can't believe how much great advice you guys have to give...I'm gonna explore the zfs drobo option and let you guys know how it goes...part of me wants and can afford a drobo, but I've heard too many horror stories to go that route...hence why I ended up here hah
  12. Smashmouthftball New Member

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    Smashmouthftball, Feb 6, 2013

    Thanks so much so far, I'll let you know how it goes from here

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