BTRFS - Have you tried it?

Fruity · 2010-09-03 12:09:34

I'm interested in what you think about this new filesystem. It seems to have lots of useful features, and according to a few reviews I have read is as fast as ext2/3/4 in some tests, faster in others, and slower in some. though (un)interestingly filestytem creation is almost near instantaneous.

Graph chart of a few filesytem comparisons I wondered across http://www.t2-project.org/zine/4/ (out of date)

And this is a blatant rip from wikipedia:

Btrfs, thus far, has implemented:[11][12]

    * Online volume growth and shrinking
    * Online block device addition and removal
    * Online defragmentation
    * Online balancing (movement of objects between block devices to balance load)
    * Transparent compression (currently zlib)
    * Subvolumes (separately-mountable filesystem roots)
    * Snapshots (writeable, copy-on-write copies of subvolumes)
    * File cloning (copy-on-write on individual files, or byte ranges thereof)
    * Object-level (RAID1-like) mirroring, (RAID0-like) striping
    * Checksums on data and metadata (currently CRC-32C[13])
    * In-place conversion (with rollback) from ext3/4 to Btrfs[14]
    * File system seeding[15] (Btrfs on read-only storage used as a copy-on-write backing for a writeable Btrfs)
    * User-defined transactions
    * Block discard support (reclaims space on some virtualization setups or improves wear leveling on SSDs by notifying the underlying device that storage is no longer in use)

Planned features include:

    * Object-level (RAID5-like and RAID6-like) parity-based striping
    * Online and offline filesystem check
    * Incremental dumps
    * Data deduplication[1]

Btrfs, when complete, is expected to offer a feature set comparable to Oracle Corporation's ZFS

One feature for me which stands out is online defrag, I know linux filesystems dont suffer in the same way as windoze, but I use torrents a fair bit, and rip a lot of my dvd's for the NAS, and over time my filestem fragmentation must be a mess, anyhoo... Snapshots is another nice feature.

BTFS is in the kernel already, though still very much in the delevopment stage, fedora has offered it as a special option on it's latest release. It seems the future might be BTFS, ZFS for the masses? Persoanlly I havent tried it, as it doesnt support encryption or raid.

Whats your thoughts?

Last edited by Fruity (2010-09-03 12:10:28)

hatten · 2010-09-03 13:28:37

I'm using it since a few months, I wanted to stripe three harddrives, my hdd's ain't that big, and decided to try btrfs instead of the now-outdated raid. Not a single complaint, but I haven't tried anymore special features except for striping and converting ext->btrfs, both of which were very easy.

Labello · 2010-09-03 14:03:33

i am using it in compressed and ssd-mode on my desktop and in compressed-mode on my netbook. no complaints at all :-)

it seems decent and fast. i am curious whether there will be any new features/improvements/speedups in the near future xD

yejun · 2010-09-03 14:54:51

No filesystem check is the biggest drawback for now. btrfsck will give an error but without any way to fix it. Grub can't probe driver correctly sometime even when /boot on a separated partition.

Last edited by yejun (2010-09-03 14:57:07)

Labello · 2010-09-03 15:50:55

afaik grub does not support btrfs. so you should stick with ext*

yejun · 2010-09-03 16:03:40

I only have problem with grub2, because it was trying to probe root partition and failed. You can still install it manually.
Both grub and burg gave no errors.

mikesd · 2010-09-03 23:24:21

yejun wrote:

No filesystem check is the biggest drawback for now. btrfsck will give an error but without any way to fix it. Grub can't probe driver correctly sometime even when /boot on a separated partition.

I listened to a webcast by Chris Mason the other day and he hoped they would have a beta btrfsck working in the next couple of months.

I am currently using it on a couple of external drives and on my netbook's ssd. I too used the btrfs-convert tool to go from ext4 to btrfs without problems. I only have a single root partition however extlinux boots from btrfs directly. You do need to re-install extlinux after the conversion. I enabled ssd in the mount options and while I didn't take timings boot does seem faster now than on ext4. Not sure why this would be.

Cdh · 2010-09-04 00:37:16

I have it with compression on my eee 1000h as /

I have already killed the filesystem with Tuxonice which was compiled as module for the kernel and didn't work right I guess.. Haven't tried again so far.
Big problem: No fsck that can repair errors yet... I created a new one and enjoy compression on my slow hard disk.

So I would strongly recommend doing backups often.

There is this bug in 2.6.35 which makes btrfs sometimes very slow:
http://www.phoronix.com/scan.php?page=n … &px=ODQ4Nw
Does anyone know if this is fixed already in 2.6.35.4? I didn't find much to this topic...

Spacenick · 2010-09-05 17:33:02

I'm using Btrfs on an Atom D510 based server with two 1 TB harddrives in mirror mode, one of them having a 40 GB ext4 partition at the beginning.
It works charmingly and we just did a 9 day non-stop ffmpeg recoding job that was entirely on the btrfs filesystem.
Even the cron based btrfs snapshots did not create problems.
Cdh is right though, don't use non standard kernels with it and keep in mind it might be hard to repair.

taylorchu · 2010-09-06 00:07:04

I think I will stick with ext4 for a while. ext4 is stable and almost as fast as btrfs. But as soon as btrfs goes stable, I might consider switching.

bruce · 2010-09-09 04:53:30

I looked at using btrfs as it is one of the few file systems in linux with built-in compressed read/write support, but find its compression implementation too poorly executed to use at the moment...
When I do a df on my root partition when mounted with reiser4 (which I use chose to use after trying btrfs) I get:

 Filesystem            Size  Used Avail Use% Mounted on
/dev/root             463M  393M   71M  85% /

Which is fine, and when I start using more space the amount of available slowly decreases to 0 (at which point you can run into kernel oops type issues :-s ) which is faily logical...
But when trying to do the same with btrfs I get:

Filesystem            Size  Used Avail Use% Mounted on
/dev/loop0            490M  322M  169M  66% /mnt

which looks really good (ie heaps better compression performance etc), however when I try and put more files on the btrfs filesystem I get out of space errors after copying on only another 20mb and df reports:

Filesystem            Size  Used Avail Use% Mounted on
/dev/loop0            490M  328M  163M  67% /mnt

implying there's a whole pile of space there to use even though there's not... Which is difficult to deal with... (read as crap to deal with :-p )
I can also fit a little over 100mb (of randomly installed packages) more on the partition with reieser4 than with btrfs which is a big bonus imo (or big negative of btrfs)....
Their compression setup seems quite flawed to my eye, and compression is something very important to my choice of filesystem...
So in my experience btrfs isn't as yet polished enough to fulfil its potential (just for what I use it for though, I know btrfs is designed to do a whole pile of things reiser4 isn't)...

Last edited by bruce (2010-09-09 04:54:48)

Cdh · 2010-09-09 07:04:11

I guess it's a deficiency in df. There was another problem with btrfs + showing free space with df some time ago...

ehlo · 2010-09-09 12:29:23

Until it has proper fsck, I don't see any point in evaluating it

extofme · 2010-09-11 19:53:46

ehlo wrote:

Until it has proper fsck, I don't see any point in evaluating it

fsck is mostly pointless. back up your stuff if you want assurances; super-fsck-man is defenseless against failed drives and memory

i've been on the same btrfs root partition since 2.6.30, no probs, and all the benefits. be judicious about sensitive data and back it up appropriately (which you should do anyway, irrespective of FS)

do that and you'll be fine. the overwhelming majority of btrfs users appear to have only success stories, because the mailing list is relatively quiet; the folks creating btrfs are a pretty competent crowd

C Anthony

relgueta · 2010-09-12 05:21:21

yes, and works fine.

subvolume and snapshots are really incredible for test some unstable stuff.

sand_man · 2010-09-12 09:25:38

Right. I don't know much about btrfs but I know zfs doesn't have fsck either. It does have a 'scrub' command but I don't think it's quite the same.

mikesd · 2010-09-12 09:41:19

relgueta wrote:

yes, and works fine.
subvolume and snapshots are really incredible for test some unstable stuff.

schroot has support for btrfs snapshot based chroots now. Makes it easy to do this sort of thing. Set up a clean root filesystem in a subvolume and schroot can automatically create a root file system snapshot based on it. When you are done just exit the chroot and delete the snapshot.

venky80 · 2010-09-12 15:21:03

I used topwa's archboot to install arch and this is my hard drive structure

/sda1 win7 NTFS
/sda2 FAT32
/sda5 / BRTFS
/sda6 /var EXT4
/sda7 /boot EXT2
/sda8 SWAP
/sda9 /home EXT4

I selected compress and a subvolume for brtfs now i do not know how to take snapshot, could someone point me to a wiki?

falconindy · 2010-09-12 15:50:44

venky80 wrote:

I selected compress and a subvolume for brtfs now i do not know how to take snapshot, could someone point me to a wiki?

btrfs(8) has plenty of info.

Cdh · 2010-09-12 16:19:15

Not really "plenty"

subvolume snapshot <source> [<dest>/]<name>
Create a writable snapshot of the subvolume <source> with the name <name> in the <dest> directory. If <source> is not a subvolume, btrfs returns an error.

I myself have not used this features and don't really know what the standard way of doing things is.

I mean, <source> is supposed to be the name of my subvolume?
<dest>? Do I create the snapshot in a directory of the filesystem I take the snapshot of when I want to snapshot my root filesystem? When I do a subsequent snapshot will this snapshot be included then?
What happens if I omit <dest>? Will it be in the current directory? What does a snapshot look like? Is it a file that can be mounted?

falconindy · 2010-09-12 16:28:56

<source> is the source of the snapshot. <dest> is where the snapshot is going to reside. You said you made your root into its own subvol, so you could do something like this...

# mkdir /mnt/root
# mount /dev/sda2 /mnt/root
# btrfs snapshot /mnt/root/__active /mnt/root/__snapshots/2010-09-12
# umount /mnt/root
# rmdir /mnt/root

venky80 · 2010-09-12 18:20:15

falconindy wrote:

<source> is the source of the snapshot. <dest> is where the snapshot is going to reside. You said you made your root into its own subvol, so you could do something like this...
# mkdir /mnt/root
# mount /dev/sda2 /mnt/root
# btrfs snapshot /mnt/root/__active /mnt/root/__snapshots/2010-09-12
# umount /mnt/root
# rmdir /mnt/root

and how do I revert back to the sanpshot? Also i put a name to my subvolume while creating it, how can I find out what it was?

Thanks for the reply

Last edited by venky80 (2010-09-12 18:20:48)

venky80 · 2010-09-12 18:23:40

Cdh wrote:

Not really "plenty"
subvolume snapshot <source> [<dest>/]<name>
Create a writable snapshot of the subvolume <source> with the name <name> in the <dest> directory. If <source> is not a subvolume, btrfs returns an error.
I myself have not used this features and don't really know what the standard way of doing things is.
I mean, <source> is supposed to be the name of my subvolume?
<dest>? Do I create the snapshot in a directory of the filesystem I take the snapshot of when I want to snapshot my root filesystem? When I do a subsequent snapshot will this snapshot be included then?
What happens if I omit <dest>? Will it be in the current directory? What does a snapshot look like? Is it a file that can be mounted?

Thanks for your reply ...I thought still things are very unclear

Gullible Jones · 2010-09-12 20:08:02

Tried it with Meego at one point. First thing I noticed was the the install was much slower with it than ext3, as were boot and application launch speeds upon restart. Which I guess isn't surprising; from what I've heard it's not really optimized for desktop use yet.

mikesd · 2010-09-12 23:16:53

Gullible Jones wrote:

Tried it with Meego at one point. First thing I noticed was the the install was much slower with it than ext3, as were boot and application launch speeds upon restart. Which I guess isn't surprising; from what I've heard it's not really optimized for desktop use yet.

Even though it is still under heavy development I have found btrfs fine performance wise. There was a nasty regression[1] recently which had a massive effect on performance in certain situations.

[1] http://www.phoronix.com/scan.php?page=n … &px=ODQ4Nw

Arch Linux

#1 2010-09-03 12:09:34

BTRFS - Have you tried it?

#2 2010-09-03 13:28:37

Re: BTRFS - Have you tried it?

#3 2010-09-03 14:03:33

Re: BTRFS - Have you tried it?

#4 2010-09-03 14:54:51

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#5 2010-09-03 15:50:55

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#7 2010-09-03 23:24:21

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#8 2010-09-04 00:37:16

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#9 2010-09-05 17:33:02

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#10 2010-09-06 00:07:04

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#11 2010-09-09 04:53:30

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#12 2010-09-09 07:04:11

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#13 2010-09-09 12:29:23

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#15 2010-09-12 05:21:21

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