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Thread: Storage/redundancy advice.

  1. #1

    Default Storage/redundancy advice.

    I currently have openSUSE 13.1 installed on an old 320gb harddrive (BTRFS) and have been loving it! I'd like to commit more to the platform. I just bought a couple 3tb harddrives to move to.

    My question is, Is it possible to migrate to a RAID like system and have the drives mirrored?
    I'd also be happy if it was a backup as long as it is bootable. My goal is to have no downtime if one of the hdd's kicks the bucket.

    What would be an ideal setup?

    Thanks in advance for any advice you can provide.

  2. #2

    Default Re: Storage/redundancy advice.

    ImperfectLink wrote:
    > I currently have openSUSE 13.1 installed on an old 320gb harddrive
    > (BTRFS) and have been loving it! I'd like to commit more to the
    > platform. I just bought a couple 3tb harddrives to move to.
    >
    > My question is, Is it possible to migrate to a RAID like system and have
    > the drives mirrored?


    Yes

    > I'd also be happy if it was a backup as long as it is bootable. My goal
    > is to have no downtime if one of the hdd's kicks the bucket.


    What do you mean by 'no downtime'? Do you mean it literally, a
    high-availability no-break system? Do you have two machines in different
    buildings powered from different mains generating stations etc etc?

    Or do you just mean that if the system goes down, you can bring it up
    again without having to go and buy anything?

    Or that it will come back by itself?

    Or that you don't want to do any data copying after a failure?

    > What would be an ideal setup?


    As you can see, we need more information to answer that. Some people
    would say to put everything on a RAID 1. I prefer to kepp the root
    system and the data storage separate.

    Whatever you do, you still need a separate backup, preferably offline.

    > Thanks in advance for any advice you can provide.


  3. #3

    Default Re: Storage/redundancy advice.

    Thanks for your quick reply.

    Sorry I wasn't clear. I just want it to be so that if one of the drives dies, I can simply boot to the other one and be able to resume work where I left off. It doesn't need to be an automatic switch.

    I do keep offsite backup for my most important data, but to me that's just a worst case scenario.

    I tried to create a software raid using the partitioner but I'm not familiar with that sort of setup. It gives me an error that there are not enough unused devices. Do I need to format the drives for them to be seen?

  4. #4

    Default Re: Storage/redundancy advice.

    Quote Originally Posted by ImperfectLink View Post
    I currently have openSUSE 13.1 installed on an old 320gb harddrive (BTRFS) and have been loving it!.
    Be aware that there are arguments about whether BTRFS is really ready for serious use yet. For me and for my requirements, I think that it is and I'm preparing to do some exploratory work with it, but there are others who will tell you that it isn't ready.

    What would you lose if it did go badly wrong and how valuable would it be to you?

    Quote Originally Posted by ImperfectLink View Post
    ...on an old 320gb harddrive (BTRFS) ... I just bought a couple 3tb harddrives to move to.
    I'd guess that we can presume that the 3TB drives are faster and that you would rather use them for most things, simply because they are newer and bigger?

    Quote Originally Posted by ImperfectLink View Post
    My question is, Is it possible to migrate to a RAID like system and have the drives mirrored?
    I'd also be happy if it was a backup as long as it is bootable. My goal is to have no downtime if one of the hdd's kicks the bucket.
    .
    Is RAID RAID-like enough for you?

    The 'old-fashioned' way would be to select a filesystem like ext4 and use the multi-disk driver to make a raid array. The 'more modern' (and, for more modern you can read 'not as fully debugged', or 'available with extra excitement' if you like) is to use something like BTRFS (and the only other thing sufficiently like BTRFS is ZFS - ZFS, in general, is more mature, and there are two Linux implementations, both of which are somewhat questionable (licensing, speed, maturity-of-implementation) but could be the answer in the short-to-medium term); ZFS/BTRFS incorporate the 'making a RAID array' part in with the filesystem set-up, so you no longer need the multi-disk driver to stitch together partitions into a raid array.

    It all depends a bit on what you are realistically trying to protect against (and, if a fairly well populated drive goes south on a big RAID array, remember that the rebuild time could be significant - so, if immediate availability, even with one drive down is your thing, you might not be getting that because with the array degraded the performance may not be sufficient for you to feel that the system was actually 'available', even if technically it was 'available, but slow' - more of an issue with RAID 5/6 rather than 1 (or 0, for that matter, in hybrid modes such as 10, but we are getting ahead of ourselves), but do be realistic - even the best system will struggle to give you 'so you wouldn't notice' performance all throughout the problem!

    I take it that you have enough SATA (or whatever) ports for the number of disk drives that you want to connect.

    (sorry, DJH replied while I was writing this - must get my fingers upgraded!)

  5. #5

    Default Re: Storage/redundancy advice.

    I'm not particularly worried about losing more than a days work as I also have an external drive to backup to and I also alternate between laptop and desktop enough that my working data (3d modeler) is usually in a few places.

    I dont want to spend time setting up my software just the way I want it if I don't need to. I've also come to enjoy stuff like snapper so I was hoping to go btrfs. My external hdd is ext4.

    How would I go about transitioning from my 320gb btrfs to dual 3tb?

  6. #6
    Join Date
    Feb 2009
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    Default Re: Storage/redundancy advice.

    On 2014-01-31 16:26, ImperfectLink wrote:
    > I tried to create a software raid using the partitioner but I'm not
    > familiar with that sort of setup. It gives me an error that there are
    > not enough unused devices. Do I need to format the drives for them to be
    > seen?


    First you have to create raid partitions on each drive, and then create
    the raid device. It is not that obvious in the partitioner.

    --
    Cheers / Saludos,

    Carlos E. R.
    (from 12.3 x86_64 "Dartmouth" at Telcontar)

  7. #7

    Default Re: Storage/redundancy advice.

    Thanks for the replies fellas. I decided to go with BTRFS on the first/primary disk and set a backup to the second with EXT4 formatting.

    I have a couple followup questions if I may.

    When I originally set up openSUSE on my system, I selected LVM Based Proposal, Separate Home Partition and BTRFS default. Was it a mistake to use LVM and BTRFS options together?

    My original hdd is both unbootable and unmountable at this point and I believe it is because of the volumes. Is there a way for me to view the (enencrypted) volumes on that drive now or are they essentially lost?

    Thanks for helping me understand BTRFS a bit better.

  8. #8
    Join Date
    Feb 2009
    Location
    Spain
    Posts
    25,547

    Default Re: Storage/redundancy advice.

    On 2014-02-01 19:16, ImperfectLink wrote:

    > When I originally set up openSUSE on my system, I selected LVM Based
    > Proposal, Separate Home Partition and BTRFS default. Was it a mistake to
    > use LVM and BTRFS options together?


    In my opinion, you should not be using things like LVM or BTRFS unless
    you understand them. They have specific features, and in case of
    problems, they are more difficult to handle.

    For instance; I can be considered an expert in several Linux areas, yet
    I refrain from using LVM because I'm not confident on being able to
    repair it.

    --
    Cheers / Saludos,

    Carlos E. R.
    (from 12.3 x86_64 "Dartmouth" at Telcontar)

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