help with btrfs send

help with btrfs send

[frantz.hacquard]

 Hi,

 I don't know if it's the good place to ask my question.
 I'm a french student who studies IT.
 I'm working on a project with the btrfs filesystem on Gentoo 64 bits.
 I have to create snapshots and to compare the differences between them 
 (new files, deleted files, modified files...).
 So i tried to use btrfs send -i old-snap new-snap.
 To make this command working i created my snapshots thanks to the -r 
 option.
 However i only see on the standard output many weird characters but i 
 don't understand them.
 I know it's still in developement but is it working ?
 I tried with kernel 3.6.2 and 3.7.0

 Thanks for help.

Re: help with btrfs send

[Rory Campbell-Lange]

On 24/10/12, frantz.hacquard (frantz.hacquard@ensi-bourges.fr) wrote:
> I don't know if it's the good place to ask my question.
> I'm a french student who studies IT.
> I'm working on a project with the btrfs filesystem on Gentoo 64 bits.
> I have to create snapshots and to compare the differences between
> them (new files, deleted files, modified files...).
> So i tried to use btrfs send -i old-snap new-snap.
> To make this command working i created my snapshots thanks to the -r
> option.
> However i only see on the standard output many weird characters but
> i don't understand them.
> I know it's still in developement but is it working ?
> I tried with kernel 3.6.2 and 3.7.0

Hi Frantz

The output of 'btrfs send' is in binary format. You can read more about
what is contained in the data stream in Jonathan Corbet's posting at LWN
here http://lwn.net/Articles/506244/

You'd normally do send/receive something like this:

    btrfs send /backup/start | btrfs receive /destination

There are also some notes on the btrfs wiki here, by Alexander Block
https://btrfs.wiki.kernel.org/index.php/Design_notes_on_Send/Receive
however I believe these are a bit out of date now.

You can look at the latest code for btrfs-progs here:
http://git.kernel.org/?p=linux/kernel/git/mason/btrfs-progs.git;a=summary
you may in particular want to look at Alexander Block's patchset here:
http://git.kernel.org/?p=linux/kernel/git/mason/btrfs-progs.git;a=commit;h=f1c24cd80dfd037407cdee85181646adca6dd5bb

-- 
Rory Campbell-Lange
rory@campbell-lange.net

Re: help with btrfs send

[Arne Jansen]

On 10/24/2012 06:53 PM, frantz.hacquard wrote:
> Hi,
> 
> I don't know if it's the good place to ask my question.
> I'm a french student who studies IT.
> I'm working on a project with the btrfs filesystem on Gentoo 64 bits.
> I have to create snapshots and to compare the differences between them
> (new files, deleted files, modified files...).
> So i tried to use btrfs send -i old-snap new-snap.
> To make this command working i created my snapshots thanks to the -r
> option.
> However i only see on the standard output many weird characters but i
> don't understand them.

If you want to dissect the contents, you can pull the tool fardump
from here:

git://git.kernel.org/pub/scm/linux/kernel/git/arne/far-progs.git

'far' is the name we're going to give the stream format.

-arne

> I know it's still in developement but is it working ?
> I tried with kernel 3.6.2 and 3.7.0
> 
> Thanks for help.
> -- 
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Re: help with btrfs send

[David Sterba]

On Wed, Oct 24, 2012 at 06:23:32PM +0100, Rory Campbell-Lange wrote:
> The output of 'btrfs send' is in binary format. You can read more about
> what is contained in the data stream in Jonathan Corbet's posting at LWN
> here http://lwn.net/Articles/506244/
> 
> You'd normally do send/receive something like this:
> 
>     btrfs send /backup/start | btrfs receive /destination

We should not try to send the binary data into a terminal anyway, I'm
sending a patch to fix that.

thanks,
david