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Thread: Leap 42.3 If btfs is good why wasn't it suggested for /home?

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    Default Leap 42.3 If btfs is good why wasn't it suggested for /home?

    I have a several years experience running Linux I ran Suse about 16 years ago when I bought it in a book store.
    I decided to try Opensuse and have never used btfs or xfs. I usually use ext4.
    I just wondered if btfs is stable enough for the os why is xfs recommended for /home?

    PS. is it possible to install on /dev/sdb without erasing /dev/sda?

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    Default Re: Leap 42.3 If btfs is good why wasn't it suggested for /home?

    Le 02/11/2017 à 05:16, slickrick66 a écrit :

    > I just wondered if btfs is stable enough for the os why is xfs
    > recommended for /home?
    >
    > PS. is it possible to install on /dev/sdb without erasing /dev/sda?
    >
    >


    yes it is.

    Of course there are some differences from ext4

    for me, essentially, the BTRFS snapshot system needs much space on the
    partition (100Gb recommended if available), else it need a snapshot
    management, but it gives the snapshot security...

    there is no way to make a file system smaller with xfs

    jdd

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    Default Re: Leap 42.3 If btfs is good why wasn't it suggested for /home?

    > I just wondered if btfs is stable enough for the os why is xfs recommended for /home?
    nothing to do with stability. (I believe) that since every file change is stored (COW) on btrfs then snapshots would become too much.

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    Default Re: Leap 42.3 If btfs is good why wasn't it suggested for /home?

    Quote Originally Posted by slickrick66 View Post
    I decided to try Opensuse and have never used btfs or xfs. I usually use ext4.
    ...
    PS. is it possible to install on /dev/sdb without erasing /dev/sda?
    If you are just going to install openSUSE on a laptop of yours for everyday use I would stick with EXT4 (that's what I'm currently doing).
    If you are going to test openSUSE and willing to learn a lot, then go with the default (and be prepared to study accordingly).
    My understanding is that BTRFS and XFS might have several advantages in a corporate environment, but might be overkill for "home" use, especially if you are not used to the tricks needed by those filesystems.

    PS: of course it is possible to install the system on the device you want, just select the "Expert partitioner" button when at the disk layout proposal screen. If you are used to Linux that should be straightforward; if not so, just ask here on the forum.
    BTW, welcome back to openSUSE!
    Leap 15.1 Gnome on i7 4720HQ + Geforce GTX960M

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    Default Re: Leap 42.3 If btfs is good why wasn't it suggested for /home?

    Phoronix did a "Btrfs, EXT4, XFS, F2FS" comparison in 2015: <https://www.phoronix.com/scan.php?pa...x-43-ssd&num=1>.

    Also, there's this, about 2 years old, "UNIX Men" comparison of EXT4, Btrfs and XFS: <https://www.unixmen.com/review-ext4-vs-btrfs-vs-xfs/>.

    You pays your money and, you takes your choice.

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    Default Re: Leap 42.3 If btfs is good why wasn't it suggested for /home?

    On Thu, 02 Nov 2017 04:16:01 +0000, slickrick66 wrote:

    > I just wondered if btfs is stable enough for the os why is xfs
    > recommended for /home?


    Snapshots, for one - stability is only one "qualification" (if you will)
    for selecting a particular filesystem for a particular use.

    Say, for example, you're running virtual machines. Do you want snapshots
    to duplicate virtual hard drives every single time a snapshot is taken?
    (Answer: No, you don't - I actually tried it, and performance - another
    "qualification" - tanked on the system).

    Jim

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    Default Re: Leap 42.3 If btfs is good why wasn't it suggested for /home?

    I have no inside knowledge, but I can guess...

    There probably is no problem using BTRFS for /home (or for virtual disk storage), but only if configured specifically for that and other scenarios... In other words, implementing would require a pretty fair amount of work and research/testing that hasn't been done by anyone on a large enough scale today (possibly a future project for TW guinea pigs?)

    Various articles have listed desirable features you'd want in all scenarios... particularly file integrity checks, and journaling. Apparently BTRFS does those exceptionally well with very little latency. So, BTRFS can be cool for runtime in general.

    But,
    the downsides are also commonly described, including
    COW - Although it's nice to attain an exceptionally high level of integrity, it comes with a high performance cost. COW is nice for those systems that can tolerate a bit of write latency, but Users on Workstations tend to expect instantaneous responsiveness.
    Snapshot storage - A common question in these openSUSE forums, many Users are surprised by storage requirements when they suddenly run out of disk space.
    LVM - Writes on LVM in general can be very slow.
    Fragmentation - I'm not sure how this is that different than other file systems but is perhaps exacerbated by COW latency. In any case, if you maintain at least 30% free space and once a year perhaps <move> files that are frequently over-written/updated/changed to another partition or disk and back again, the problem is addressed.
    Large RAID - Is your array close to 15 disks?

    For those who might want to explore an alternative to BTRFS which has been around a lot longer and has some pretty interesting features of its own, Red Hat recommends ZFS (and does not recommend BTRFS). I've played around with ZFS a little bit, it's very interesting but requires a steep and extensive learning curve (and when was the last time we in openSUSE really had to "learn" a file system?)

    Some interesting links to recent or current info...
    A lot of the configurations described for virtual disks should be considered if you're deploying BTRFS for /home

    SUSE 12 SP3 Storage
    Most of the BTRFS content is relevant, but not the section on "duperemove" because the package isn't available. You can probably still get it though, if you want to build from source(github) which doesn't look difficult. Instead of duperemove, I've experimented with bedup which has been around a bit longer. Yes, the documentation considers BTRFS as viable virtualization storage... when configured accordingly.
    https://www.suse.com/documentation/s...tor_admin.html

    BTRFS and virtual disks
    https://superuser.com/questions/7053...rfs-filesystem

    BTRFS - describes some extensive testing comparing BTRFS to other file systems,
    https://serverfault.com/questions/85...lesystem-btrfs

    Plenty of IMO,
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    Default Re: Leap 42.3 If btfs is good why wasn't it suggested for /home?

    On Fri, 03 Nov 2017 15:36:02 +0000, tsu2 wrote:

    > There probably is no problem using BTRFS for /home (or for virtual disk
    > storage), but only if configured specifically for that and other
    > scenarios... In other words, implementing would require a pretty fair
    > amount of work and research/testing that hasn't been done by anyone on a
    > large enough scale today (possibly a future project for TW guinea pigs?)


    Really specifically, my setup was using btrfs for hosting VDI files for
    VirtualBox - I found that starting 9 VMs at the same time (it's a beefy
    machine), the system would become totally nonresponsive because something
    would trigger a snapshot during that process. Snapshots with multiple GB
    files are (or were, this was on 42.1 or earlier) high impact to
    performance.

    I switched to using XFS, since it doesn't have that snapshot feature, and
    that fixed the performance issue (that was recommended when I asked
    questions about it of someone with btrfs internals knowledge). Their
    recommendation was that that wasn't a good use case for btrfs, and that I
    should look at a different filesystem.

    Jim

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    Default Re: Leap 42.3 If btfs is good why wasn't it suggested for /home?

    When the partition if formatted BTRFS,
    you can exclude specific directories from snapshotting.

    Even our current default BTRFS root partition is configured to exclude a large number of directories, primarily runtime that are always re-created and have no value being saved, and files that are deployed to RAM.

    Before BTRFS can be deployed widespread on a partition other than root, all these directories that should be excluded (and maybe some of them might not apply to everyone) need to be identified.

    Your comment about snapshot issues for Virtualbox on the /home partition is commonly encountered by KVM/QEMU users because for those the default storage is in the root partition.

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    Default Re: Leap 42.3 If btfs is good why wasn't it suggested for /home?

    On Sat, 04 Nov 2017 16:06:01 +0000, tsu2 wrote:

    > you can exclude specific directories from snapshotting.


    Cool, I hadn't realized that. Going to have to use that on my docker
    directory structure.

    For me, though, on the home partition, snapshots didn't make a lot of
    sense anyways.

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