Hello, I'm currently running a similar setup. It's running a blustore OSD with 1 NVME device for db/wal devices. That NVME device is not large enough to support 160GB db partition per osd, so I'm stuck with 50GB each. Currently haven't had any issues with slowdowns or crashes. The cluster is relatively idle. Up to 10k iops at peaks with 50/50 read/write io distribution. Thought throughput is a different matter It's more like 10:1 with 1GBps/100MBps. I have noticed that the best latencies I can get from using raid0 on sas devices is running them in Writeback and disabled readahead on controler. It might be that you will have different results. I wish you luck in testing it. On Thu, Sep 6, 2018 at 4:14 PM David Turner <drakonstein@xxxxxxxxx> wrote: > > The official ceph documentation recommendations for a db partition for a 4TB bluestore osd would be 160GB each. > > Samsung Evo Pro is not an Enterprise class SSD. A quick search of the ML will allow which SSDs people are using. > > As was already suggested, the better option is an HBA as opposed to a raid controller. If you are set on your controllers, write-back is fine as long as you have BBU. Otherwise you should be using write-through. > > On Thu, Sep 6, 2018, 8:54 AM Muhammad Junaid <junaid.fsd.pk@xxxxxxxxx> wrote: >> >> Thanks. Can you please clarify, if we use any other enterprise class SSD for journal, should we enable write-back caching available on raid controller for journal device or connect it as write through. Regards. >> >> On Thu, Sep 6, 2018 at 4:50 PM Marc Roos <M.Roos@xxxxxxxxxxxxxxxxx> wrote: >>> >>> >>> >>> >>> Do not use Samsung 850 PRO for journal >>> Just use LSI logic HBA (eg. SAS2308) >>> >>> >>> -----Original Message----- >>> From: Muhammad Junaid [mailto:junaid.fsd.pk@xxxxxxxxx] >>> Sent: donderdag 6 september 2018 13:18 >>> To: ceph-users@xxxxxxxxxxxxxx >>> Subject: help needed >>> >>> Hi there >>> >>> Hope, every one will be fine. I need an urgent help in ceph cluster >>> design. We are planning 3 OSD node cluster in the beginning. Details are >>> as under: >>> >>> Servers: 3 * DELL R720xd >>> OS Drives: 2 2.5" SSD >>> OSD Drives: 10 3.5" SAS 7200rpm 3/4 TB >>> Journal Drives: 2 SSD's Samsung 850 PRO 256GB each Raid controller: PERC >>> H710 (512MB Cache) OSD Drives: On raid0 mode Journal Drives: JBOD Mode >>> Rocks db: On same Journal drives >>> >>> My question is: is this setup good for a start? And critical question >>> is: should we enable write back caching on controller for Journal >>> drives? Pls suggest. Thanks in advance. Regards. >>> >>> Muhammad Junaid >>> >>> >>> >> _______________________________________________ >> ceph-users mailing list >> ceph-users@xxxxxxxxxxxxxx >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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