> On 20 Oct 2015, at 11:28, Luis Periquito <periquito@xxxxxxxxx> wrote: > >>> One trick I've been using in my ceph clusters is hiding a slow write >>> backend behind a fast journal device. The write performance will be of >>> the fast (and small) journal device. This only helps on write, but it >>> can make a huge difference. >>> >> >> Do you mean an external filesystem journal? What filesystem? ext4/xfs? >> I tried that on a physical machine and it worked wonders with both of them, even though data wasn't journaled and hit the platters - I don't yet understand how that was possible but the benchmark just flew. >> > > I just have a raw partition in the journal device (SSD) and point "osd > journal" to that block device (something like "osd journal = > /dev/vgsde/journal-8"). So no filesystem in the journal device. Then > the osd data is in a local HDD using normal XFS filesystem. > > To help this I do have usually big amounts of RAM (average 6G per > OSD), so the buffered writes to the spindle can take it's time to > flush. Oh. I think that's a pretty normal scenario actually. Jan _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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