Den tors 20 dec. 2018 kl 22:45 skrev Vladimir Brik <vladimir.brik@xxxxxxxxxxxxxxxx>: > Hello > I am considering using logical volumes of an NVMe drive as DB or WAL > devices for OSDs on spinning disks. > The documentation recommends against DB devices smaller than 4% of slow > disk size. Our servers have 16x 10TB HDDs and a single 1.5TB NVMe, so > dividing it equally will result in each OSD getting ~90GB DB NVMe > volume, which is a lot less than 4%. Will this cause problems down the road? Well, apart from the reply you already got on "one nvme fails all the HDDs it is WAL/DB for", the recommendations are about getting the best out of them, especially for the DB I suppose. If one can size stuff up before, then following recommendations is a good choice, but I think you should test using it for WALs for instance, and bench it against another host with data, wal and db on the HDD and see if it helps a lot in your expected use case. -- May the most significant bit of your life be positive. _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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