Bump! i would love the thoughts about this ! On Fri, Sep 8, 2017 at 7:44 AM, Richard Hesketh < richard.hesk...@rd.bbc.co.uk> wrote:
> Hi, > > Reading the ceph-users list I'm obviously seeing a lot of people talking > about using bluestore now that Luminous has been released. I note that many > users seem to be under the impression that they need separate block devices > for the bluestore data block, the DB, and the WAL... even when they are > going to put the DB and the WAL on the same device! > > As per the docs at http://docs.ceph.com/docs/master/rados/configuration/ > bluestore-config-ref/ this is nonsense: > > > If there is only a small amount of fast storage available (e.g., less > than a gigabyte), we recommend using it as a WAL device. If there is more, > provisioning a DB > > device makes more sense. The BlueStore journal will always be placed on > the fastest device available, so using a DB device will provide the same > benefit that the WAL > > device would while also allowing additional metadata to be stored there > (if it will fix). [sic, I assume that should be "fit"] > > I understand that if you've got three speeds of storage available, there > may be some sense to dividing these. For instance, if you've got lots of > HDD, a bit of SSD, and a tiny NVMe available in the same host, data on HDD, > DB on SSD and WAL on NVMe may be a sensible division of data. That's not > the case for most of the examples I'm reading; they're talking about > putting DB and WAL on the same block device, but in different partitions. > There's even one example of someone suggesting to try partitioning a single > SSD to put data/DB/WAL all in separate partitions! > > Are the docs wrong and/or I am missing something about optimal bluestore > setup, or do people simply have the wrong end of the stick? I ask because > I'm just going through switching all my OSDs over to Bluestore now and I've > just been reusing the partitions I set up for journals on my SSDs as DB > devices for Bluestore HDDs without specifying anything to do with the WAL, > and I'd like to know sooner rather than later if I'm making some sort of > horrible mistake. > > Rich > -- > Richard Hesketh > > > > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > > -- *Alejandro Comisario* *CTO | NUBELIU* E-mail: alejandro@nubeliu.comCell: +54 9 11 3770 1857 _ www.nubeliu.com
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