Re: Questions on incremental backups

[Daniel Mizyrycki <mzdaniel@glidelink.net>]

On 07/18/14 06:40, Russell Coker wrote:
>>> Displaying backups is an issue of backup software. It is above the
>>> level that BTRFS development touches. While people here can probably
>>> offer generic advice on backup software it's not the topic of the
>>> list.
>>
>> As said, I don't mind developing the software. But, is the required
>> information easily available? Is there a way to get a diff, something
>> like a list of changed/added/removed files between snapshots?
>
> Your usual diff utility will do it.  I guess you could parse the output of
> btrfs send.
Following this thought, one step closer in getting a text diff can be to 
use fardump. It takes a btrfs send binary stream and outputs the send 
instructions in plaintext. 
(https://kernel.googlesource.com/pub/scm/linux/kernel/git/arne/far-progs).
It certainly would be awesome if btrfs-progs could have an extra 
parameter to just generate the list of changed/added/removed files 
between snapshots as all the needed infrastructure is already in place.

>
>> And, finally, nobody has mentioned on the possibility of merging
>> multiple snapshots into a single snapshot. Would this be possible, to
>> create a snapshot that contains the most recent version of each file
>> present across all of the snapshots (including files which may be
>> present in only one of the snapshots)?
>
> There is no btrfs functionality for that.  But I'm sure you could do something
> with standard Unix utilities and copying files around.
Sure, but the management of data deduplication is left to the user 
(presumably using cp --reflink) which is not trivial.
Does anybody knows how safe it is to use duperemove or bedup?
Any recommendations on how to effectively deduplicate btrfs at this point?