If it helps, I’m seeing about a 3GB DB usage for a 3TB OSD about 60% full. This is with a pure RBD workload, I believe this can vary depending on what your Ceph use case is.
From: ceph-users [mailto:[email protected]] On Behalf Of David Turner Sent: 06 September 2018 14:09 To: Muhammad Junaid <[email protected]> Cc: [email protected] Subject: Re: [ceph-users] help needed 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 <[email protected] <mailto:[email protected]> > 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 <[email protected] <mailto:[email protected]> > wrote: Do not use Samsung 850 PRO for journal Just use LSI logic HBA (eg. SAS2308) -----Original Message----- From: Muhammad Junaid [mailto:[email protected] <mailto:[email protected]> ] Sent: donderdag 6 september 2018 13:18 To: [email protected] <mailto:[email protected]> Subject: [ceph-users] 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 [email protected] <mailto:[email protected]> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com <https://protect-eu.mimecast.com/s/0HpOCPZVLUkPOFzbJ40?domain=lists.ceph.com>
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