On Fri, 29 Mar 2019 01:22:06 -0400 Erik McCormick wrote: > Hello all, > > Having dug through the documentation and reading mailing list threads > until my eyes rolled back in my head, I am left with a conundrum > still. Do I separate the DB / WAL or not. > You clearly didn't find this thread, most significant post here but read it all: http://lists.ceph.com/pipermail/ceph-users-ceph.com/2019-March/033799.html In short, a 30GB DB(and thus WAL) partition should do the trick for many use cases and will still be better than nothing. Christian > I had a bunch of nodes running filestore with 8 x 8TB spinning OSDs > and 2 x 240 GB SSDs. I had put the OS on the first SSD, and then split > the journals on the remaining SSD space. > > My initial minimal understanding of Bluestore was that one should > stick the DB and WAL on an SSD, and if it filled up it would just > spill back onto the OSD itself where it otherwise would have been > anyway. > > So now I start digging and see that the minimum recommended size is 4% > of OSD size. For me that's ~2.6 TB of SSD. Clearly I do not have that > available to me. > > I've also read that it's not so much the data size that matters but > the number of objects and their size. Just looking at my current usage > and extrapolating that to my maximum capacity, I get to ~1.44 million > objects / OSD. > > So the question is, do I: > > 1) Put everything on the OSD and forget the SSDs exist. > > 2) Put just the WAL on the SSDs > > 3) Put the DB (and therefore the WAL) on SSD, ignore the size > recommendations, and just give each as much space as I can. Maybe 48GB > / OSD. > > 4) Some scenario I haven't considered. > > Is the penalty for a too small DB on an SSD partition so severe that > it's not worth doing? > > Thanks, > Erik > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > -- Christian Balzer Network/Systems Engineer chibi@xxxxxxx Rakuten Communications _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
 |