On Wed, Feb 22, 2017 at 1:52 PM, Florent B <flor...@coppint.com> wrote: > On 02/21/2017 06:43 PM, John Spray wrote: >> On Tue, Feb 21, 2017 at 5:20 PM, Florent B <flor...@coppint.com> wrote: >>> Hi everyone, >>> >>> I use a Ceph Jewel cluster. >>> >>> I have a CephFS with some directories at root, on which I defined some >>> layouts : >>> >>> # getfattr -n ceph.dir.layout maildata1/ >>> # file: maildata1/ >>> ceph.dir.layout="stripe_unit=1048576 stripe_count=3 object_size=4194304 >>> pool=cephfs.maildata1" >>> >>> >>> My problem is that the default "data" pool contains 44904 EMPTY objects >>> (size of pool=0), and duplicates of my pool cephfs.maildata1. >> This is normal: the MDS stores a "backtrace" for each file, that >> allows it to find the file by inode number when necessary. Usually, >> when files are in the first data pool, the backtrace is stored along >> with the data. When your files are in a different data pool, the >> backtrace is stored on an otherwise-empty object in the first data >> pool. >> > > Ok, and what is the purpose of these empty objects ? is there any > documentation on this ?
As mentioned above, it's for situations where the MDS needs to find a file by its inode number. Backtraces are part of the internal on-disk format, which is not currently part of what's documented. John _______________________________________________ ceph-users mailing list ceph-users@lists.ceph.com http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
