Increasing pg_num will lead to several slow requests and cluster freeze, but  
due to creating pgs operation , for what I’ve seen until now.
During the creation period all the request are frozen , and the creation period 
take a lot of time even for 128 pgs.

I’ve observed that during creation period most of the OSD goes at 100% of their 
performance capacity. I think that without operation running in the cluster 
I’ll be able to upgrade pg_num quickly without causing down time several times.

Matteo

> Il giorno 02 gen 2017, alle ore 15:02, [email protected] ha scritto:
> 
> Well, as the doc said:
>> Set or clear the pause flags in the OSD map. If set, no IO requests will be 
>> sent to any OSD. Clearing the flags via unpause results in resending pending 
>> requests.
> If you do that on a production cluster, that means your cluster will no
> longer be in production :)
> 
> Depending on your needs, but ..
> Maybe you want do this operation as fast as possible
> Or maybe you want to make that operation as transparent as possible,
> from a user point of view
> 
> You may have a look at osd_recovery_op_priority &
> osd_client_op_priority, they might be interesting for you
> 
> On 02/01/2017 14:37, Matteo Dacrema wrote:
>> Hi All,
>> 
>> what happen if I set pause flag on a production cluster?
>> I mean, will all the request remain pending/waiting or all the volumes 
>> attached to the VMs will become read-only?
>> 
>> I need to quickly upgrade placement group number from 3072 to 8192 or better 
>> to 165336 and I think doing it without client operations will be much faster.
>> 
>> Thanks
>> Regards
>> Matteo
>> 
>> 
>> 
>> 
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