btrfs userspace question - where's the utility to dump/restore?

btrfs userspace question - where's the utility to dump/restore?

[Valdis Kletnieks]

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So I'm looking at playing with btrfs, and I start looking at the
userspace pieces I'll need.  What I can't find is an equivalent
of the ext[34] "dump/restore" package to dump data to an external
backup device. Is 'tar cf --acls --selinux --xattrs /external/fs.dump'
as good as it gets, or is something else recommended?

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Re: btrfs userspace question - where's the utility to dump/restore?

[Hugo Mills]

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On Thu, Jan 17, 2013 at 03:05:35PM -0500, Valdis Kletnieks wrote:
> So I'm looking at playing with btrfs, and I start looking at the
> userspace pieces I'll need.  What I can't find is an equivalent
> of the ext[34] "dump/restore" package to dump data to an external
> backup device. Is 'tar cf --acls --selinux --xattrs /external/fs.dump'
> as good as it gets, or is something else recommended?

   tar doesn't handle reflinks(+), so the above won't quite give you a
complete duplicate. In the btrfs tool, there's send/receive, which
should(*) be sufficient to deal with reflinks.

   Hugo.

(+) aka CoW copies, or snapshots
(*) I regret to say that I've not had the opportunity to play with
send/receive myself yet, so I can't advise on the details of making it
work yet.

-- 
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Re: btrfs userspace question - where's the utility to dump/restore?

[Valdis.Kletnieks]

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On Thu, 17 Jan 2013 22:18:19 +0000, Hugo Mills said:

> On Thu, Jan 17, 2013 at 03:05:35PM -0500, Valdis Kletnieks wrote:
> > So I'm looking at playing with btrfs, and I start looking at the
> > userspace pieces I'll need.  What I can't find is an equivalent
> > of the ext[34] "dump/restore" package to dump data to an external
> > backup device. Is 'tar cf --acls --selinux --xattrs /external/fs.dump'
> > as good as it gets, or is something else recommended?
>
>    tar doesn't handle reflinks(+), so the above won't quite give you a
> complete duplicate. In the btrfs tool, there's send/receive, which
> should(*) be sufficient to deal with reflinks.

So I decided to try it out on the filesystem that I stash all my music
(mostly because I can survive without that filesystem if I trash it, and
I have a known good backup).

Apparently, send/receive isn't in the manpage, which is why I didn't
see it.  Fortunately, there's --help

[~] btrfs send --help
usage: btrfs send <command> <args>

    btrfs send [-v] [-i <subvol>] [-p <parent>] <subvol>
        Send the subvolume to stdout.

[~] btrfs send -v /mp3 > /disk2/backups/mp3.btrfs
ERROR: /mp3 is not read-only.
[~] mount -o remount,ro /mp3
[~] btrfs send -v /mp3 >| /disk2/backups/mp3.btrfs
ERROR: /mp3 is not read-only.

Bah. Obviously this isn't anywhere near as easy as it is for ext4.

/me wanders off to find more caffeine...

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