ZFS for Time Machine and/or Data

Discussion in 'OS X Mavericks (10.9)' started by haravikk, Jan 17, 2014.

  1. haravikk macrumors 65816

    May 1, 2005
    Okay, so one of the recurring complaints about OS X is the lack of a more modern file-system. While Core Storage shows a great deal of promise, we're still lacking any protection against bit-rot, and since my main block of storage is 3tb I'm thinking I really should get more serious about it, as I've already noticed blips and crackles in my oldest music files, so god knows what else has degraded with time and migration from different drives.

    Anyway, while I made a switch from SSD for OS and HDDs for files to using a Fusion Drive, I'm hoping to get a bigger SSD when I replace my current computer. I'm thinking that what I'll do is partition the SSD into 25% for Mac OS X and Applications, 25% for Bootcamp, and the rest will be the SSD part of a Fusion Drive for my files (the HDD side will be a RAID-5 to give at least partial protection against drive failures).

    I'll also have a separate volume for Time Machine (HDD only).

    I'm thinking the Time Machine volume is the most important one to protect since the files should be in there long-term, and in theory any files being backed up should be recent and thus unlikely to have suffered bit-rot yet. However, I'm wondering if anyone has managed to get Time Machine to run from a ZFS volume? I know there's a trick that sometimes works by creating an HFS disk image on a volume and pointing Time Machine to that, but will it work when running from a ZFS volume? If so then I believe it would add protection to the disk image?

    I believe OS X won't boot from ZFS at all, so that rules it out for OS and Applications, but that's not such a big issue I think since both are fairly easy to just re-install if required.

    That leaves my user folders volume. First question for that is… will ZFS work for that? Obviously ZFS will need to be available before logging in, but is that as simple as just waiting a while before logging in? What if I wanted to have FileVault 2 enabled on my OS partition?

    On a related note, I know that MacZFS doesn't support encryption yet, but do any of the other drivers? Can ZFS be used as a file system on a Core Storage volume in order to add encryption (and/or Fusion Drive) that way?

    Anyway, I'd appreciate hearing how other people have their systems setup with ZFS, why, and what advantages/disadvantages they've found to that setup (e.g - quirks or annoyances with how OS X lets you operate that way).

    For example, I'd really like to avoid having to split my home folder across multiple volumes, or using a files-specific volume; I did that in the past and found it to be nothing but a hassle as sym-linking my ~/Movies folder to point at another volume just provided nothing but annoyances thanks to the inconsistency with which various apps handle sym-links, even though the whole point is that they're supposed to be invisible.
  2. Bear macrumors G3

    Jul 23, 2002
    Sol III - Terra
    Layering an HFS disk image on top of ZFS means that you can't do a system disk restoration from it.

    If you're worried about the shape of your backups, I suggest having at least 2 backups, because stuff happens.

    As it stands a directly connected Time Machine disk has a recovery partition. I like that, it gives me more recovery partitions to boot from.
  3. haravikk, Jan 17, 2014
    Last edited: Jan 17, 2014

    haravikk thread starter macrumors 65816

    May 1, 2005
    I already have a NAS as well, and it backups up to CrashPlan's cloud service as well, so I'm definitely covered for copies of files. I just like the idea of having error correction on my direct attached devices so I can just forget about file integrity, and only have to restore from slower backups if something more disastrous happens such as hardware failure, plus I'm changing my storage setup anyway.

    True, but then I can easily add recovery partitions to other disks myself for that (including one or more of the disks I'll be putting Time Machine on); I have one on a USB stick for emergencies too.

    Also another question I had is; are there any alternatives to ZFS for Mac? For example, btrfs for Linux seems interesting, and may be better if I'm using hardware RAID anyway (since ZFS really prefers to just software RAID all disks). Interestingly MacPorts has a btrfs-progs port available, but I'm not sure what it's for (whether it allows creation of btrfs volumes etc.), but I don't have any spare disks (or rather, a means of connecting them) to test with.
  4. grahamperrin macrumors 601


    Jun 8, 2007
    That's only partly true.

    More than once in the past I added ZFS software to Recovery OS so that the OS could read from ZFS on locally attached storage.

    More recently, and simply: I used a normal Recovery OS to restore from a Time Machine backup on ZFS on FreeNAS (network attached storage).

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