using discard from qemu guest when snapshot exist, fill the rbd layer with zeroes and use more space

using discard from qemu guest when snapshot exist, fill the rbd layer with zeroes and use more space

[Alexandre DERUMIER]

Hi,

I'm using fstrim inside my qemu guests to remove unused space from the rbd storage.

This is working fine, but I just notice that if a snapshot exist,

It just do the reverse, it's filling the snasphot with zeroes, and the total cluster space is growing.

It's is possible to avoid that ?


Regards,

Alexandre

Re: using discard from qemu guest when snapshot exist, fill the rbd layer with zeroes and use more space

[Jason Dillaman]

There is a "rbd_skip_partial_discard" configuration option which can
be set to true.  When enabled, discard will avoid zeroing holes if the
discard extent is in the middle of an object.

On Fri, Jun 17, 2016 at 5:10 AM, Alexandre DERUMIER <aderumier@odiso.com> wrote:
> Hi,
>
> I'm using fstrim inside my qemu guests to remove unused space from the rbd storage.
>
> This is working fine, but I just notice that if a snapshot exist,
>
> It just do the reverse, it's filling the snasphot with zeroes, and the total cluster space is growing.
>
> It's is possible to avoid that ?
>
>
> Regards,
>
> Alexandre
> --
> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in
> the body of a message to majordomo@vger.kernel.org
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-- 
Jason

Re: using discard from qemu guest when snapshot exist, fill the rbd layer with zeroes and use more space

[Alexandre DERUMIER]

>>There is a "rbd_skip_partial_discard" configuration option which can 
>>be set to true. When enabled, discard will avoid zeroing holes if the 
>>discard extent is in the middle of an object. 

Thanks Jason . I had tried it some week ago, and my fstrim was hanging.
It'll do more test next week.

It must be defined on client right ?

[client]
rbd_skip_partial_discard = true



----- Mail original -----
De: "Jason Dillaman" <jdillama@redhat.com>
À: "aderumier" <aderumier@odiso.com>
Cc: "ceph-devel" <ceph-devel@vger.kernel.org>
Envoyé: Vendredi 17 Juin 2016 15:21:53
Objet: Re: using discard from qemu guest when snapshot exist, fill the rbd layer with zeroes and use more space

There is a "rbd_skip_partial_discard" configuration option which can 
be set to true. When enabled, discard will avoid zeroing holes if the 
discard extent is in the middle of an object. 

On Fri, Jun 17, 2016 at 5:10 AM, Alexandre DERUMIER <aderumier@odiso.com> wrote: 
> Hi, 
> 
> I'm using fstrim inside my qemu guests to remove unused space from the rbd storage. 
> 
> This is working fine, but I just notice that if a snapshot exist, 
> 
> It just do the reverse, it's filling the snasphot with zeroes, and the total cluster space is growing. 
> 
> It's is possible to avoid that ? 
> 
> 
> Regards, 
> 
> Alexandre 
> -- 
> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in 
> the body of a message to majordomo@vger.kernel.org 
> More majordomo info at http://vger.kernel.org/majordomo-info.html 



-- 
Jason 
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Re: using discard from qemu guest when snapshot exist, fill the rbd layer with zeroes and use more space

[Jason Dillaman]

Definitely broken -- I've opened a new tracker ticket to get it fixed [1].

[1] http://tracker.ceph.com/issues/16386

On Sat, Jun 18, 2016 at 5:29 AM, Alexandre DERUMIER <aderumier@odiso.com> wrote:
>>>Thanks Jason . I had tried it some week ago, and my fstrim was hanging.
>>>It'll do more test next week.
>>>
>>>It must be defined on client right ?
>>>
>>>[client]
>>>rbd_skip_partial_discard = true
>
>
> Just tested again, fstrim is totally hanging
>
> I have attached the client.client.log in debug verbose, the log start when fstrim start
>
> ----- Mail original -----
> De: "aderumier" <aderumier@odiso.com>
> À: dillaman@redhat.com
> Cc: "ceph-devel" <ceph-devel@vger.kernel.org>
> Envoyé: Samedi 18 Juin 2016 09:40:40
> Objet: Re: using discard from qemu guest when snapshot exist, fill the rbd layer with zeroes and use more space
>
>>>There is a "rbd_skip_partial_discard" configuration option which can
>>>be set to true. When enabled, discard will avoid zeroing holes if the
>>>discard extent is in the middle of an object.
>
> Thanks Jason . I had tried it some week ago, and my fstrim was hanging.
> It'll do more test next week.
>
> It must be defined on client right ?
>
> [client]
> rbd_skip_partial_discard = true
>
>
>
> ----- Mail original -----
> De: "Jason Dillaman" <jdillama@redhat.com>
> À: "aderumier" <aderumier@odiso.com>
> Cc: "ceph-devel" <ceph-devel@vger.kernel.org>
> Envoyé: Vendredi 17 Juin 2016 15:21:53
> Objet: Re: using discard from qemu guest when snapshot exist, fill the rbd layer with zeroes and use more space
>
> There is a "rbd_skip_partial_discard" configuration option which can
> be set to true. When enabled, discard will avoid zeroing holes if the
> discard extent is in the middle of an object.
>
> On Fri, Jun 17, 2016 at 5:10 AM, Alexandre DERUMIER <aderumier@odiso.com> wrote:
>> Hi,
>>
>> I'm using fstrim inside my qemu guests to remove unused space from the rbd storage.
>>
>> This is working fine, but I just notice that if a snapshot exist,
>>
>> It just do the reverse, it's filling the snasphot with zeroes, and the total cluster space is growing.
>>
>> It's is possible to avoid that ?
>>
>>
>> Regards,
>>
>> Alexandre
>> --
>> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
>
>
> --
> Jason
> --
> To unsubscribe from this list: send the line "unsubscribe ceph-devel" in
> the body of a message to majordomo@vger.kernel.org
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-- 
Jason
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