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Thread: Decision to use BTRFS in 13.2?

  1. #1
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    Default Decision to use BTRFS in 13.2?

    This is the earliest I've ever taken a look at a distro in development, openSUSE 13.2 milestone 0.

    Installed into VMware Workstation 10.

    Amused to see the mixture of 12.3 graphics and 13.1 documentation, but I understand those are minor issues at this point.

    Am most interested in finding BTRFS is the default FS, is BTFRS considered sufficiently stable today for likely implementation or is it mainly offered for wide spread testing at this point?

    As soon as I saw BTRFS, I started looking up recent information about it...

    - Regarding SSD, it looks like various related options are supported which I recognize.
    https://wiki.archlinux.org/index.php...#Mount_options
    - No recent benchmarks, but old (<2yrs) articles suggest SSD optimizations cannot overcome the extra overhead BTRFS apparently implements for its other features.
    - This article and related comments were posted within only the past couple weeks as of this writing. I hope they will be addressed quickly
    http://etbe.coker.com.au/2014/04/26/...us-april-2014/

    Am also curious about implementation of the tmpfs mount points (7 of them! plus the swap and physical disk), they are 999mb each although I only allocated 8GB physical disk and 2GB RAM total to the VM. Assuming those tmpfs partitions are maximum and not fully allocated values (how could they be?) and not knowing why each of those mount points were created, I wonder if fewer mount points might have some benefits? So, for instance on a physical disk drive creating so many partitions causes inefficient use of space and potential out of space issues... I don't know if that would be true for tmpfs. Similarly, I'd be curious about the reason for creating so many mount points, on a physical drive reasons could include isolation (isolating errors to what is in that partition), controlling fragmentation, minimizing maintenance issues (data on different partitions managed differently).

    In fact, the errors and overall scenario described in the article written a few weeks I referenced above might have been controlled by better partitioning.

    I've also played around a little bit with the ZFS Linux kernel extensions for similar benefits BTFRS provides, ie volumes across multiple devices, RAID volumes, snapshots.

    TSU

  2. #2
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    Default Re: Decision to use BTRFS in 13.2?

    Quote Originally Posted by tsu2 View Post
    Am most interested in finding BTRFS is the default FS, is BTFRS considered sufficiently stable today for likely implementation or is it mainly offered for wide spread testing at this point?
    The installer wanted to use "btrfs" for 13.2M0, but I told it to use "ext4" instead. I'm guessing that I will have to pay attention during installs.

    I tried "btrfs" during the pre-release testing of 13.1, but decided that it was not for me. I might consider trying again for further pre-release testing of 13.2 - still waiting for Milestone1 here. My plan is for "ext4" on the final release.

    Concerns that I saw with "btrfs" and 13.1 milestones:

    • a lot of space is tied up with snapshots;
    • it seemed to interfere with grub (probing for other linux systems did not work properly);
    • there were no obvious benefits from using "btrfs" - it seemed that I would have to learn quite a bit to take advantage of the snapshots.
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    Default Re: Decision to use BTRFS in 13.2?

    BTRFS looks to be the new default. I think it is a bad idea. It does appear to be stable now and the recovery utilities are improving. But the problem will be that new users who do not understand the ramification of snapshots are going to be bitten with not having enough space allocated. At this point it is unclear how much space would be needed since snapshot size is dependent on the amount of changes you make to the files. IMO snapshots should be .set off by default and if a user wants them they can turn them on presumably knowing the ramifications. If default is on we will be very busy here on the board about 4-6 weeks after the release when people start running out of space and standard tools say they have plenty. Perhaps a warning at install may medicate the problems but I doubt it toaster users generally don't read

    BTRFS looks to be good for complex installation like servers but I really doubt the utility for a simple Desktop.


    Tmpfs memory is shared I believe and when the physical is used up it will pop into swap. I suspect it may be problematic in very low memory systems. Great if you have 8+ gig not so much if only 1

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    Default Re: Decision to use BTRFS in 13.2?

    Quote Originally Posted by gogalthorp View Post
    BTRFS looks to be the new default. I think it is a bad idea.
    I agree.

    And with the concerns of tsu2 and nrickert.

    And with this:
    Perhaps a warning at install may (mitigate) the problems but I doubt it toaster users generally don't read
    "Take a Walk on a Sunny Day, Greet everyone along the way, and Make Somebody Smile, Today"
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  5. #5

    Default Re: Decision to use BTRFS in 13.2?

    Maybe the installer should check whether the machine is amd64 and the machine should have at least 4GB RAM and at least 200GB free HD space to default for BTRFS otherwise it defaults to use ext4?

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    Default Re: Decision to use BTRFS in 13.2?

    On 2014-05-24 02:06, gogalthorp wrote:

    > BTRFS looks to be good for complex installation like servers but I
    > really doubt the utility for a simple Desktop.


    It could be interesting for external backup media, because you
    automatically get current and old versions of each file (ok, you need to
    trigger one snapshot in between backups).

    Another interesting point is that it supports compression (not stable
    yet, but not sure about it). This is a feature that Windows has had for
    more than a decade, natively, in ntfs. Ext2/3/4 had provision of it, but
    it was never implemented.

    A read/write compressed filesystem is interesting for storage of things
    that can be compressed a lot, like mail, or logs. And backups, of
    course, for use with rsync or simimilar, instead of tar.gz.


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    Default Re: Decision to use BTRFS in 13.2?

    On 2014-05-24 09:06, FurciferPardalis wrote:
    >
    > Maybe the installer should check whether the machine is amd64 and the
    > machine should have at least 4GB RAM and at least 200GB free HD space to
    > default for BTRFS otherwise it defaults to use ext4?


    That's an interesting idea.

    --
    Cheers / Saludos,

    Carlos E. R.

    (from 13.1 x86_64 "Bottle" (Minas Tirith))

  8. #8

    Default Re: Decision to use BTRFS in 13.2?

    Quote Originally Posted by gogalthorp View Post
    But the problem will be that new users who do not understand the ramification of snapshots are going to be bitten with not having enough space allocated. At this point it is unclear how much space would be needed since snapshot size is dependent on the amount of changes you make to the files. IMO snapshots should be .set off by default and if a user wants them they can turn them on presumably knowing the ramifications. If default is on we will be very busy here on the board about 4-6 weeks after the release when people start running out of space and standard tools say they have plenty.
    While I am looking forward to having a more in depth play with BTRFS, I think that you are exactly right here. Newbs will select BTRFS (or, more exactly, not do anything to deselect BTRFS), not really be concious of anything unusual having happened and then be very surprised when it goes pear shaped some time later.

    One question, though: are any of the existing tools being re-written to give more information in the case of snapshots being active (or new utils being written)? One thing that I don't know is whether there will be new versions of things like du and df that will either go to 'extra information mode' if snapshots are present, or show zero space for snapshots, if snapshots aren't active. Its probably potentially a bit of a mess either way, with either backward compatibility or deceptive information being issues. And doesn't that part of the issue exist for LVM already?

    Quote Originally Posted by gogalthorp View Post
    Perhaps a warning at install may medicate the problems but I doubt it toaster users generally don't read
    Another thing to get ahead might be a wiki page for the 'Why Haven't I Got the Free Disk Space That I Think I Should' info; at least then, the question could be answered with a simple link. I doubt it will do much to reduce the number of questions, but there will be less writing in each answer. But still, some medication could be required...(but then, I thought that about systemd, and that wasn't as bad as expected).

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    Default Re: Decision to use BTRFS in 13.2?

    Quote Originally Posted by nrickert View Post
    Concerns that I saw with "btrfs" and 13.1 milestones:

    • a lot of space is tied up with snapshots;
    • it seemed to interfere with grub (probing for other linux systems did not work properly);
    • there were no obvious benefits from using "btrfs" - it seemed that I would have to learn quite a bit to take advantage of the snapshots.
    Been using btrfs with Snapper on logical root partion for Tumbleweed (12.3 through 13.1) where the updates are large, frequent, and done with zypper dup. Kept it down around 20GB partition, after reducing the default snapshot retention by >50%. Monitoring used space with btrfs command-line tools is not difficult. Not had any btrfs stability issues, not doing compression or anything fancy.

    No problems with Grub2 in my multi-boot configuration. Grub2 is in a separate /boot, logical partition (512MB) belonging to Tumbleweed. No problems with Grub2 management, although the other partitions have all been current and older openSUSE releases.

    Noticed some extra overhead on my notebook wrt disk i/o activity, at boot time and immediately after updates.

    Also concerned about btrfs as default. More concerned about Snapper as default for btrfs on root partition, especially if the current snapshot retention levels are retained for 13.2 and Snapper is an "opt-out" feature. It should be an "opt-in", especially for the default desktop system.
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  10. #10
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    Default Re: Decision to use BTRFS in 13.2?

    Quote Originally Posted by FurciferPardalis View Post
    Maybe the installer should check whether the machine is amd64 and the machine should have at least 4GB RAM and at least 200GB free HD space to default for BTRFS otherwise it defaults to use ext4?
    I think that is a good suggestion.

    But, I still think BTRFS should not be the default choice, in any case. The seasoned users can always make a conscious choice to use it when they install, if they feel it is superior for their needs. And, it is the seasoned users who will stop to consider such things when installing.
    "Take a Walk on a Sunny Day, Greet everyone along the way, and Make Somebody Smile, Today"
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