Unable to set pg_num property of pool "data"

Unable to set pg_num property of pool "data"

[hemant surale]

Hi Ceph Community ,
     I am facing problem while I am explicitly  trying to set
"pg_number" of "data" pool.

--------------------------------------------------------------------------------------------------------------------
root@third-virtual-machine:~# ceph osd pool set data pg_num 100
2012-08-29 15:08:52.388446 mon <- [osd,pool,set,data,pg_num,100]
2012-08-29 15:08:52.388924 mon0 -> 'specified pg_num 100 <= current 200' (-22)


root@third-virtual-machine:~# ceph osd pool get data pg_num
2012-08-29 15:09:04.788365 mon <- [osd,pool,get,data,pg_num]
2012-08-29 15:09:04.788833 mon0 -> 'PG_NUM: 200' (0)

-----------------------------------------------------------------------------------------------------------------
Why is it not working to set pg_number to 100. The cmd is executed
while ceph is running.
(ceph v. 0.36, ubuntu 11.10)


Regards,
hemant surale.

Re: Unable to set pg_num property of pool "data"

[Sylvain Munaut]

Hi,

>      I am facing problem while I am explicitly  trying to set
> "pg_number" of "data" pool.

You can't change pg_num of an existing pool, you can only specify this
number when creating the pool.
Support for online pg split/merge is an upcoming feature.

Cheers,

    Sylvain

Re: Unable to set pg_num property of pool "data"

[Wido den Hollander]

On 08/29/2012 11:42 AM, hemant surale wrote:
> Hi Ceph Community ,
>       I am facing problem while I am explicitly  trying to set
> "pg_number" of "data" pool.
>
> --------------------------------------------------------------------------------------------------------------------
> root@third-virtual-machine:~# ceph osd pool set data pg_num 100
> 2012-08-29 15:08:52.388446 mon <- [osd,pool,set,data,pg_num,100]
> 2012-08-29 15:08:52.388924 mon0 -> 'specified pg_num 100 <= current 200' (-22)
>

Could you show us the output of the following command?

$ ceph osd dump -o -|grep pg_num

It seems like you are trying to decrease the number of PGs?

>
> root@third-virtual-machine:~# ceph osd pool get data pg_num
> 2012-08-29 15:09:04.788365 mon <- [osd,pool,get,data,pg_num]
> 2012-08-29 15:09:04.788833 mon0 -> 'PG_NUM: 200' (0)
>
> -----------------------------------------------------------------------------------------------------------------
> Why is it not working to set pg_number to 100. The cmd is executed
> while ceph is running.
> (ceph v. 0.36, ubuntu 11.10)
>

I recommend upgrading to Ubuntu 12.04.1 with Ceph 0.48.1

Wido

>
> Regards,
> hemant surale.
> --
> 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
>

Re: Unable to set pg_num property of pool "data"

[Wido den Hollander]

CC back to the list.

On 08/29/2012 12:15 PM, hemant surale wrote:
> $  ceph osd dump -o -|grep pg_num
>
> pg_pool 0 'data' pg_pool(rep pg_size 1 crush_ruleset 0 object_hash
> rjenkins pg_num 200 pgp_num 192 lpg_num 2 lpgp_num 2 last_change 78
> owner 0)

So you are trying to decrease the number of PGs.

Now, I'm not sure if that is supported. But why would you want to do this?

Wido

> pg_pool 1 'metadata' pg_pool(rep pg_size 1 crush_ruleset 1 object_hash
> rjenkins pg_num 192 pgp_num 192 lpg_num 2 lpgp_num 2 last_change 39
> owner 0)
> pg_pool 2 'rbd' pg_pool(rep pg_size 1 crush_ruleset 2 object_hash
> rjenkins pg_num 192 pgp_num 192 lpg_num 2 lpgp_num 2 last_change 41
> owner 0)
>   wrote 1108 byte payload to -
>
>
>
> ----------------------------------------------------------------------------------------------------------------------
> On Wed, Aug 29, 2012 at 3:21 PM, Wido den Hollander <wido@widodh.nl> wrote:
>> On 08/29/2012 11:42 AM, hemant surale wrote:
>>>
>>> Hi Ceph Community ,
>>>        I am facing problem while I am explicitly  trying to set
>>> "pg_number" of "data" pool.
>>>
>>>
>>> --------------------------------------------------------------------------------------------------------------------
>>> root@third-virtual-machine:~# ceph osd pool set data pg_num 100
>>> 2012-08-29 15:08:52.388446 mon <- [osd,pool,set,data,pg_num,100]
>>> 2012-08-29 15:08:52.388924 mon0 -> 'specified pg_num 100 <= current 200'
>>> (-22)
>>>
>>
>> Could you show us the output of the following command?
>>
>> $ ceph osd dump -o -|grep pg_num
>>
>> It seems like you are trying to decrease the number of PGs?
>>
>>
>>>
>>> root@third-virtual-machine:~# ceph osd pool get data pg_num
>>> 2012-08-29 15:09:04.788365 mon <- [osd,pool,get,data,pg_num]
>>> 2012-08-29 15:09:04.788833 mon0 -> 'PG_NUM: 200' (0)
>>>
>>>
>>> -----------------------------------------------------------------------------------------------------------------
>>> Why is it not working to set pg_number to 100. The cmd is executed
>>> while ceph is running.
>>> (ceph v. 0.36, ubuntu 11.10)
>>>
>>
>> I recommend upgrading to Ubuntu 12.04.1 with Ceph 0.48.1
>>
>> Wido
>>
>>>
>>> Regards,
>>> hemant surale.
>>> --
>>> 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
>>>
>>

Re: Unable to set pg_num property of pool "data"

[Tommi Virtanen]

On Wed, Aug 29, 2012 at 9:42 AM, Wido den Hollander <wido@widodh.nl> wrote:
> So you are trying to decrease the number of PGs.
>
> Now, I'm not sure if that is supported. But why would you want to do this?

Support for pg shrinking will come pretty much exactly at the same
time as support for pg growing -- soon, but not yet.

Re: Unable to set pg_num property of pool "data"

[hemant surale]

I was able to increase the PG_num property but only problem is to
reduce it. Anyways thanks for your  valuable reply.


- Hemant Surale.

On Wed, Aug 29, 2012 at 7:13 PM, Tommi Virtanen <tv@inktank.com> wrote:
> On Wed, Aug 29, 2012 at 9:42 AM, Wido den Hollander <wido@widodh.nl> wrote:
>> So you are trying to decrease the number of PGs.
>>
>> Now, I'm not sure if that is supported. But why would you want to do this?
>
> Support for pg shrinking will come pretty much exactly at the same
> time as support for pg growing -- soon, but not yet.

Re: Unable to set pg_num property of pool "data"

[Sylvain Munaut]

> I was able to increase the PG_num property but only problem is to
> reduce it. Anyways thanks for your  valuable reply.

AFAIK the old tool allowed you to do that but it didn't really work
internally if the pool wasn't empty.
In the new version it has been removed completely because it wasn't
really working anyway (despite what the command line might lead you to
believe).

And it will be implemented soon-ish properly.

Cheers,

    Sylvain

Re: Unable to set pg_num property of pool "data"

[hemant surale]

Thanx for your valuable information..


-
Hemant Surale

On Thu, Aug 30, 2012 at 4:37 PM, Sylvain Munaut
<s.munaut@whatever-company.com> wrote:
>> I was able to increase the PG_num property but only problem is to
>> reduce it. Anyways thanks for your  valuable reply.
>
> AFAIK the old tool allowed you to do that but it didn't really work
> internally if the pool wasn't empty.
> In the new version it has been removed completely because it wasn't
> really working anyway (despite what the command line might lead you to
> believe).
>
> And it will be implemented soon-ish properly.
>
> Cheers,
>
>     Sylvain