Does the bluestore min alloc size apply for 4k block-size files [1]? [1] https://github.com/ceph/ceph/blob/master/src/common/config_opts.h#L1063 On Wed, Apr 19, 2017 at 4:51 PM, Gregory Farnum <gfarnum@xxxxxxxxxx> wrote: > On Wed, Apr 19, 2017 at 1:49 PM, Pavel Shub <pavel@xxxxxxxxxxxx> wrote: >> 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. > > I can't speak with authority on bluestore, but at those total sizes I > think you're just seeing the effects of the internal journaling. > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com -- Jason _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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