Re: [SPAM] Changing pg_num => RBD VM down !

[Florent B <florent@xxxxxxxxxxx>]

Of course but it does not explain why VMs stopped...
That full system slows down, OK, but brutal stop...

On 03/14/2015 07:00 PM, Andrija Panic wrote:

changin PG number - causes LOOOT of data rebalancing (in my case was 80%) 

which I learned the hard way...

On 14 March 2015 at 18:49, Gabri Mate <mailinglist@xxxxxxxxxxxxxxxxxxx> wrote:

I had the same issue a few days ago. I was increasing the pg_num of one
pool from 512 to 1024 and all the VMs in that pool stopped. I came to
the conclusion that doubling the pg_num caused such a high load in ceph
that the VMs were blocked. The next time I will test with small
increments.


On 12:38 Sat 14 Mar     , Florent B wrote:
> Hi all,
>
> I have a Giant cluster in production.
>
> Today one of my RBD pools had the "too few pgs" warning. So I changed
> pg_num & pgp_num.
>
> And at this moment, some of the VM stored on this pool were stopped (on
> some hosts, not all, it depends, no logic)
>
> All was running fine for months...
>
> Have you ever seen this ?
> What could have caused this ?
>
> Thank you.
>
>
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> ceph-users@xxxxxxxxxxxxxx
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--

Andrija Panić

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