Re: Beginner questions

Bastiaan Visser <bastiaan@xxxxxxx> · Thu, 16 Jan 2020 18:54:47 +0100

I would definitely go for Nautilus. there are quite some optimizations that went in after mimic.

Bluestore DB size usually ends up at either 30 or 60 GB.
30 GB is one of the sweet spots during normal operation. But during compaction, ceph writes the new data before removing the old, hence the 60GB.Next sweetspot is 300/600GB. any size between 60 and 300 will never be unused.

DB Usage is also dependent on ceph usage, object storage is known to use a lot more db space than rbd images for example.

Op do 16 jan. 2020 om 17:46 schreef Dave Hall <kdhall@xxxxxxxxxxxxxx>:

    Hello all.
    Sorry for the beginner questions...

    I am in the process of setting up a small (3 nodes, 288TB) Ceph
      cluster to store some research data.  It is expected that this
      cluster will grow significantly in the next year, possibly to
      multiple petabytes and 10s of nodes.  At this time I'm expected a
      relatively small number of clients, with only one or two actively
      writing collected data - albeit at a high volume per day.

    Currently I'm deploying on Debian 9 via ceph-ansible.  

    Before I put this cluster into production I have a couple
      questions based on my experience to date:

    Luminous, Mimic, or Nautilus?  I need stability for this
      deployment, so I am sticking with Debian 9 since Debian 10 is
      fairly new, and I have been hesitant to go with Nautilus.  Yet
      Mimic seems to have had a hard road on Debian but for the efforts
      at Croit.  

      Statements on the Releases page are now making more sense to
        me, but I would like to confirm that Nautilus is the right
        choice at this time?

    Bluestore DB size:  My nodes currently have 8 x 12TB drives (plus
      4 empty bays) and a PCIe NVMe drive.  If I understand the
      suggested calculation correctly, the DB size for a 12 TB Bluestore
      OSD would be 480GB.  If my NVMe isn't big enough to provide this
      size, should I skip provisioning the DBs on the NVMe, or should I
      give each OSD 1/12th of what I have available?  Also, should I try
      to shift budget a bit to get more NVMe as soon as I can, and redo
      the OSDs when sufficient NVMe is available?

    Thanks.
    -Dave

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