Re: Forever growing data in ceph using RBD image

[Alphe Salas <asalas@kepler.cl>]

Alphe Salas
I.T ingeneer

On 07/17/2014 12:47 PM, Christoph Hellwig wrote:
> On Thu, Jul 17, 2014 at 10:11:09AM -0400, Alphe Salas wrote:
>> Usually when I talk to dev team about this problem they tell me that the
>> real problem is the lack of trim in XFS, but my own analysis shows that the
>> real problem is ceph internal way to handle data. It is ceph that never
>> discard any replicas and never "clean" itself to only keep records of the
>> data in use.
>
> XFS supports TRIM just fine - with -o discard it will issue TRIMs on
> unlink, and with fstrim you can do it explicitly.  Note that the online
> discard might be very slow for all Linux filesystems, although I've not
> actually tested it on top of RBD.
>
I will test it again probably the point I missed it that you have to 
unmount / remount the XFS RBD image in order to see the data disapear 
from the real disk space old in ceph. I will try it today and comeback 
with copy /paste of ceph -s etc..


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