Mhddfs – Combine Several Smaller Partition into One Large Virtual Storage

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13 Responses

  1. Vilial says:

    I don’t know maybe it is outdated but I’ve just lost control over VPS, because the /etc/fstab record present here is incorrectly formed.

    It should not contain spaces separating folders in the beginning.

    See man mhddfs for correct example.

  2. C. R. Zamana says:

    MHDDFS has one GIGANTIC advantage over LVM or RAID-0: if you ever lose one of the disks, you’ll lose only the data that was on that disk, and not the whole data of the combined filesystem.

    Considering this, mhddfs is the simplest solution for joining several disks/partitions/folders into one lógica volume.

    Redundancy and backup should be considered as complement, of course.

  3. Anon says:

    What you want for this task is LVM2. It does what you describe for this fuse based filesystem, with the added advantage that the LVM2 device is a true combination of the underlying devices. So a single big file, larger than any single disk, but smaller than the sum of the small disks, will still fit.

  4. Derek Broughton says:

    I’m afraid your “elaboration” on choosing MhddFs over LVM hasn’t helped at all. Both LVM and Mhddfs “combine … storage pools”. One does it below the level of the filesystem, the other does it above. That does nothing to suggest why I should choose MHDDFS. Mhddfs is, no doubt, simpler to use — but the overhead! Dismissing that with a single short line in the “Cons” column seems to be a disservice. Not even mentioning LVM in such an article is a bigger one.

  5. trapexit says:

    My want to check out mergerfs. It’s similar to mhddfs but actively maintained and has more features.

  6. Mayuresh Mulye says:

    Excellent article :)

  7. Rafael Rios Saavedra says:

    Could you elaborate on how this compares to LVM ?

    Thanks forehand

    • Ravi Saive says:

      LVM is a always be preferred way but it allows us to combine disparate storage pools together, where as Mhddfs is a highly recommended as it’s FUSE based file system that allows us to join or combine several partitions into one large single virtual filesystem mount point as explained in this article.

      • Anon says:

        > that allows us to join or combine several partitions

        LVM2 also allows the joining or combining of several partitions into a single large device. LVM2 will use a partition, or the whole disk, depending on what you tell it to do. There is zero reason to use this fuse system (and incur the fuse overhead) when LVM2 already does everything it does, better.

  8. Alfonzo Garboon says:

    I don’t know that I had ever heard anyone say that “RAID has always remained notorious for loss of storage reliability.” I thought improving reliability was one of the reasons for using RAID. I understand that uses more disk space for a quantity of data. Actually, I’m not certain I understand why you brought it up at all.

    For that matter, you’re going to have to transfer the files to the other disks somehow, so your computer will be doing that work and taking at least the time to transfer. I don’t see that it’s going to save a lot of time and energy over just to picking a number of files and copying them to one of the new disks, going to lunch, picking another group and copying, etc. I don’t know why you think “This certainly is not a good idea…”

    Having said that, the MHDDFS looks like an interesting solution to the original problem you posed. It particularly has the advantage that you don’t have to know where on the three disks a particular file was saved, assuming you use 60GB of storage to store 30GB of files. You have only one disk directory/catalog to search. In fact, that may be the big advantage I see with the system.

    • Anon says:

      > I don’t know that I had ever heard anyone say that “RAID has always remained notorious for loss of storage reliability.” I thought improving reliability was one of the reasons for using RAID.

      That is the very reason to use RAID. This statement should be a tip-off to everyone that the author likely does not know what he is talking about, and the remainder of the suggestions for using this mhddfs fuse filesystem should be considered suspect.

      • maggi says:

        Well that depends on the type of your RAID.
        RAID0 will stripe all the data over the drives, so if any of them fails, the whole virtual drive will be ruined, and you have no chance to get your data back. So the risk increases with every disk in the array.
        RAID1 will give you a better availability, since it mirrors the data on two disks. If one fails, the other one will still be OK and hold the data.

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