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<mailto: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 [cid:D87E97BC-3D4F-4F8A-AC12-37B6FD3C2E40] This message (including any attachments) may be privileged or confidential. If you have received it by mistake, please notify the sender by return e-mail and delete this message from your system. Any unauthorized use or dissemination of this message in whole or in part is strictly prohibited. S3S rejects any liability for the improper, incomplete or delayed transmission of the information contained in this message, as well as for damages resulting from this e-mail message. S3S cannot guarantee that the message received by you has not been intercepted by third parties and/or manipulated by computer programs used to transmit messages and viruses. _______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com<mailto:ceph-users@lists.ceph.com> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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