On Wed, Apr 19, 2017 at 4:33 PM, Gregory Farnum <gfarnum@xxxxxxxxxx> wrote: > On Wed, Apr 19, 2017 at 1:26 PM, Pavel Shub <pavel@xxxxxxxxxxxx> wrote: >> Hey All, >> >> I'm running a test of bluestore in a small VM and seeing 2x overhead >> for each object in cephfs. Here's the output of df detail >> https://gist.github.com/pavel-citymaps/868a7c4b1c43cea9ab86cdf2e79198ee >> >> This is on a VM with all daemons & 20gb disk, all pools are of size 1. >> Is this the expected amount of overhead per object? Is there anyway to >> tweak bluestore settings? > > You're going to need to be clearer about what you mean by 2x overhead. > Bluestore itself has a minimum size beneath which it will journal > objects and then copy them into place, which might be considered 2x > overhead. If you're talking about total number of cluster-wide disk > ops, there's also a CephFS log which journals metadata updates that > get flushed out to backing objects later, which might be considered 2x > overhead. But I don't know what you mean just based on a ceph df. :) > -Greg Sorry, I meant the disk space taken up by the files. I have a dataset with lots of small files, my sample set 2.5gb in total size and 5gb on a filesystem with a 4kb block size. When put the files inside ceph bluestore they take up 6gb. Does bluestore have an internal block size? Is there a way to adjust it? For comparison I created a filestore OSD with 2kb block size and the data took up only 4.5gb. - Pavel _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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