Hi ,
I've do that before and when I try to write file into rbd. It's get
freeze.
Beside resource, is there any other reason not recommend to combined mon
and osd?
Best wishes,
Mika
2015-08-18 15:52 GMT+08:00 Межов Игорь Александрович <me...@yuterra.ru>:
> Hi!
>
> You can run mons on the same hosts, though it is not recommemned. MON
> daemon
> itself are not resurce hungry - 1-2 cores and 2-4 Gb RAM is enough in most
> small
> installs. But there are some pitfalls:
> - MONs use LevelDB as a backstorage, and widely use direct write to ensure
> DB consistency.
> So, if MON daemon coexits with OSDs not only on the same host, but on the
> same
> volume/disk/controller - it will severily reduce disk io available to OSD,
> thus greatly
> reduce overall performance. Moving MONs root to separate spindle, or
> better - separate SSD
> will keep MONs running fine with OSDs at the same host.
> - When cluster is in healthy state, MONs are not resource consuming, but
> when cluster
> in "changing state" (adding/removing OSDs, backfiling, etc) the CPU and
> memory usage
> for MON can raise significantly.
>
> And yes, in small cluster, it is not alaways possible to get 3 separate
> hosts for MONs only.
>
>
> Megov Igor
> CIO, Yuterra
>
> ------------------------------
> *От:* ceph-users <ceph-users-boun...@lists.ceph.com> от имени Luis
> Periquito <periqu...@gmail.com>
> *Отправлено:* 17 августа 2015 г. 17:09
> *Кому:* Kris Vaes
> *Копия:* ceph-users@lists.ceph.com
> *Тема:* Re: [ceph-users] Question
>
> yes. The issue is resource sharing as usual: the MONs will use disk I/O,
> memory and CPU. If the cluster is small (test?) then there's no problem in
> using the same disks. If the cluster starts to get bigger you may want to
> dedicate resources (e.g. the disk for the MONs isn't used by an OSD). If
> the cluster is big enough you may want to dedicate a node for being a MON.
>
> On Mon, Aug 17, 2015 at 2:56 PM, Kris Vaes <k...@s3s.eu> wrote:
>
>> Hi,
>>
>> Maybe this seems like a strange question but i could not find this info
>> in the docs , i have following question,
>>
>> For the ceph cluster you need osd daemons and monitor daemons,
>>
>> On a host you can run several osd daemons (best one per drive as read in
>> the docs) on one host
>>
>> But now my question can you run on the same host where you run already
>> some osd daemons the monitor daemon
>>
>> Is this possible and what are the implications of doing this
>>
>>
>>
>> Met Vriendelijke Groeten
>> Cordialement
>> Kind Regards
>> Cordialmente
>> С приятелски поздрави
>>
>>
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