Re: Another defrag question

[Liu Bo <bo.li.liu@oracle.com>]

On Thu, Feb 21, 2013 at 04:46:14PM +0100, Swâmi Petaramesh wrote:
> Hi again,
> 
> Having numerous snapshots, I prefer to ask rather than take the risk of
> exploding my storage space, better safe than sorry ;-)
> 
> "man btrfs" states :
> 
> « NOTE: defragmenting with kernels up to 2.6.37 will unlink COW-ed
> copies of data, don't use it if  you  use  snapshots,  have 
> deduplicated  your  data  or  made  copies with cp --reflink. »
> 
> I use :
> # uname -r
> 3.5.0-24-generic
> 
> ...So should I expect that defraging my BTRFS will be smart enough not
> to uncow my snapshots ? Is it actually able to defrag both the file and
> its snapshots altogether, keeping all this as a single physical copy of
> the defragged data ?

Well, there is already a patch which addresses your concern and it's
'snapshot-aware defrag' feature and now in v6, it's not merged yet.

thanks,
liubo

> 
> TIA.
> 
> -- 
> Swâmi Petaramesh <swami@petaramesh.org> http://petaramesh.org PGP 9076E32E
> Ne cherchez pas : Je ne suis pas sur Facebook.
> 
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