I am new to Ceph and start discovering its features. I used ext4 partitions (also mounted with -o discard) to place several osd on them. Then I created an erasure coded pool in this cluster. On top of this there is the rados block device which holds also an ext4 filesystem (of course mounted with -o discard). I started to create some random 1MB files with tempfile and /dev/urandom to mess the filesystem up and use all available space (256MB on my testdrive). After this I deleted everything again. To my surprise the discard-feature did not work. Ceph reports that ~256MB are used for data (after mkfs it was around 0MB). I also tried to use 'fstrim' on the mountpoint but it reports that "the discard operation is not supported". But why? It would be great to shrink the used space. Is there a way to achieve this? Or have I done something wrong? In a professional environment you may can live with filesystems that only grow. But on my small home-cluster this really is a problem. Greetings from Germany! P.S.: I use ceph version 0.80.7 as delivered with debian jessie. _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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