Install on btrfs?

mirix · 2010-06-13 17:20:26

Would it be possible to install Arch in btrfs partitions (previously created from a Sabayon live-CD)?

Cape · 2010-06-13 18:51:23

Seems like http://wiki.archlinux.org/index.php/Max … ance#BTRFS, plus i saw there's a kernel module already compiled by default.
So yes, you can. But if i was you i would re-create the filesystem anyway... Ya never know ;-)

Cdh · 2010-06-13 19:12:33

Everything in Arch can be on a btrfs partition except for /boot.
Neither grub nor grub2 can boot from btrfs so you need an extra /boot partition (100mb should be enaugh I think).

I have put my root partition on my netbook on a btrfs partition with compression activated and have /boot on an ext2 partition. So far it works really well.

goran'agar · 2010-06-14 08:25:13

Cdh wrote:

Everything in Arch can be on a btrfs partition except for /boot.
Neither grub nor grub2 can boot from btrfs so you need an extra /boot partition (100mb should be enaugh I think).
I have put my root partition on my netbook on a btrfs partition with compression activated and have /boot on an ext2 partition. So far it works really well.

FWIW, my setup is very similar. In my case, no compression but the root and home volume are dm-crypt devices with btrfs on them and it works very well.

arch0r · 2010-06-14 08:55:47

it works and i already did it, but it wasn't that fast i expected. ext4 is imo a bit more snappier than btrfs

extofme · 2010-06-14 21:14:11

just an FYI to anyone experimenting with btrfs...

install your system ( / ) INTO A DEDICATED SUBVOLUME. if you install your system into the default subvolume, you will lose a lot of flexibility when it comes to advanced hook features, such as those provided by the mkinitcpio-btrfs hook in AUR.

install into a subvolume such as /__active, then add:

rootflags=subvol=__active

to your kernel boot lines (via grub menu.lst)

demian · 2010-06-14 21:47:54

Hello extofme,

is it possible to move the installation to a subvolume if i already installed conventionally into the partition itself?
Also, since you seem to be very knowledgable on BTRFS, could you link one or two sources that explain the possibilities of BTRFS well?
I just installed btrfs in kind of a haste and would like to learn a little more about it now.

Regards,
demian

Last edited by demian (2010-06-14 21:48:35)

venky80 · 2010-06-14 22:30:51

extofme wrote:

just an FYI to anyone experimenting with btrfs...
install your system ( / ) INTO A DEDICATED SUBVOLUME. if you install your system into the default subvolume, you will lose a lot of flexibility when it comes to advanced hook features, such as those provided by the mkinitcpio-btrfs hook in AUR.
install into a subvolume such as /__active, then add:
rootflags=subvol=__active
to your kernel boot lines (via grub menu.lst)

what is a subvolume? is it a partition?

extofme · 2010-06-14 22:44:26

demian wrote:

Hello extofme,
is it possible to move the installation to a subvolume if i already installed conventionally into the partition itself?
Also, since you seem to be very knowledgable on BTRFS, could you link one or two sources that explain the possibilities of BTRFS well?
I just installed btrfs in kind of a haste and would like to learn a little more about it now.
Regards,
demian

ugh, i've been trying to get the btrfs list to answer that question for over a month:

http://www.mail-archive.com/linux-btrfs … 04964.html
http://www.mail-archive.com/linux-btrfs … 04970.html

yes and no.

yes: you can snapshot your / to a subvolume, say /__active.... BUT, copies of /bin, /etc, /usr, all that junk will remain in /, never to be used again, eventually (not initially) wasting space, because you are booting __active from now on.

no: not cleanly. after snapshotting to __active, you must manually "rm -rf" all the crap left in /. it's not really a big deal, but it's more flexible if you just install into a subvol from the start.

as for sources, i can't really think of anything offhand... i follow the mailing list so i read a lot there. but you can read this post and thread on the mkinitcpio-btrfs hook:

http://bbs.archlinux.org/viewtopic.php? … 64#p774064

and this post to arch-general (outdated, hook now supports true rollbacks, but good info):

http://mailman.archlinux.org/pipermail/ … 13008.html

basically, subvolumes and snapshots are the same thing. subvolumes start empty, snapshots are a "copy" of an existing subvolume. the cool thing here is that subvolumes can be mounted independently, with different mount options. so you could compress your /var (wait until there is an alternative to gz, too processor heavy), or encrypt (not supported by btrfs yet) your /home. also, you can add new devices on the fly and do everything online, while the system is running and mounted. on-disk compression with a lightweight algorithm like LZMA will provide BIG performance increases... your hard disk will have to seek/read significantly less. im sure there are other cool things on the map that i forgot or don't know about.

EDIT: i forgot about quotas (not implemented yet though)

i'd just head to the btrfs wiki and consume everything there.

C Anthony

Last edited by extofme (2010-06-14 22:48:57)

tavianator · 2010-06-14 22:45:13

venky80 wrote:

what is a subvolume? is it a partition?

https://btrfs.wiki.kernel.org/index.php … bvolume.3F

extofme · 2010-06-14 22:47:53

venky80 wrote:

extofme wrote:
just an FYI to anyone experimenting with btrfs...
install your system ( / ) INTO A DEDICATED SUBVOLUME. if you install your system into the default subvolume, you will lose a lot of flexibility when it comes to advanced hook features, such as those provided by the mkinitcpio-btrfs hook in AUR.
install into a subvolume such as /__active, then add:
rootflags=subvol=__active
to your kernel boot lines (via grub menu.lst)
what is a subvolume? is it a partition?

subvolumes/snapshots are like complete, internal filesystems inside the btrfs filesystem. similar to partitions, but more like lvm volume groups than standard partitions. they can have quotas/restrictions on their size, be added removed easily, and directly mounted with different mount options.

C Anthony

demian · 2010-06-14 23:11:40

Thanks for the answer.

Did i get this right: Snapshots take up 0 space initally and will grow (by the filesize) only if a file in (one of the) subvolume(s) changes? But i can still mount them as if they were normal data partitions?
Can i snapshot anything (a directory) or just the whole disk?

I'm sorry if these questions are already answered in the linked documentation. I'll definately dive into the wiki tomorrow.

Last edited by demian (2010-06-14 23:18:33)

extofme · 2010-06-14 23:40:08

demian wrote:

Thanks for the answer.
Did i get this right: Snapshots take up 0 space initally and will grow (by the filesize) only if a file in (one of the) subvolume(s) changes? But i can still mount them as if they were normal data partitions?
Can i snapshot anything (a directory) or just the whole disk?
I'm sorry if these questions are already answered in the linked documentation. I'll definately dive into the wiki tomorrow.

you got it chief.

as for snapshotting directories, thats not currently possible. i remember some talk about this on the list, but i can't remember if was even possible, or just not implemented. i'm leaning toward not implemented. you don't have to snapshot the whole disk though, you can snapshot any existing subvolume. subvolumes behave like folders; they can be nested inside each other and moved/renamed like a folder. when you delete them though, you must use the btrfs tool.

Arch Linux

#1 2010-06-13 17:20:26

Install on btrfs?

#2 2010-06-13 18:51:23

Re: Install on btrfs?

#3 2010-06-13 19:12:33

Re: Install on btrfs?

#4 2010-06-14 08:25:13

Re: Install on btrfs?

#5 2010-06-14 08:55:47

Re: Install on btrfs?

#6 2010-06-14 21:14:11

Re: Install on btrfs?

#7 2010-06-14 21:47:54

Re: Install on btrfs?

#8 2010-06-14 22:30:51

Re: Install on btrfs?

#9 2010-06-14 22:44:26

Re: Install on btrfs?

#10 2010-06-14 22:45:13

Re: Install on btrfs?

#11 2010-06-14 22:47:53

Re: Install on btrfs?

#12 2010-06-14 23:11:40

Re: Install on btrfs?

#13 2010-06-14 23:40:08

Re: Install on btrfs?

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