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 <megov@xxxxxxxxxx>:
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-bounces@xxxxxxxxxxxxxx> от имени Luis Periquito <periquito@xxxxxxxxx>
Отправлено: 17 августа 2015 г. 17:09
Кому: Kris Vaes
Копия: ceph-users@xxxxxxxxxxxxxx
Тема: Re: Questionyes. 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 <kris@xxxxxx> 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
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