On Tue, Sep 10, 2013 at 3:03 AM, Josh Durgin <josh.durgin@xxxxxxxxxxx> wrote: > On 09/09/2013 04:57 AM, Andrey Korolyov wrote: >> >> May I also suggest the same for export/import mechanism? Say, if image >> was created by fallocate we may also want to leave holes upon upload >> and vice-versa for export. > > > Import and export already omit runs of zeroes. They could detect > smaller runs (currently they look at object size chunks), and export > might be more efficient if it used diff_iterate() instead of > read_iterate(). Have you observed them misbehaving with sparse images? > > Did you meant dumpling? As I had checked some months ago cuttlefish not had such feature. >> On Mon, Sep 9, 2013 at 8:45 AM, Sage Weil <sage@xxxxxxxxxxx> wrote: >>> >>> On Sat, 7 Sep 2013, Oliver Daudey wrote: >>>> >>>> Hey all, >>>> >>>> This topic has been partly discussed here: >>>> >>>> http://lists.ceph.com/pipermail/ceph-users-ceph.com/2013-March/000799.html >>>> >>>> Tested on Ceph version 0.67.2. >>>> >>>> If you create a fresh empty image of, say, 100GB in size on RBD and then >>>> use "rbd cp" to make a copy of it, even though the image is sparse, the >>>> command will attempt to read every part of it and take far more time >>>> than expected. >>>> >>>> After reading the above thread, I understand why the copy of an >>>> essentially empty sparse image on RBD would take so long, but it doesn't >>>> explain why the copy won't be sparse itself. If I use "rbd cp" to copy >>>> an image, the copy will take it's full allocated size on disk, even if >>>> the original was empty. If I use the QEMU "qemu-img"-tool's >>>> "convert"-option to convert the original image to the copy without >>>> changing the format, essentially only making a copy, it takes it's time >>>> as well, but will be faster than "rbd cp" and the resulting copy will be >>>> sparse. >>>> >>>> Example-commands: >>>> rbd create --size 102400 test1 >>>> rbd cp test1 test2 >>>> qemu-img convert -p -f rbd -O rbd rbd:rbd/test1 rbd:rbd/test3 >>>> >>>> Shouldn't "rbd cp" at least have an option to attempt to sparsify the >>>> copy, or copy the sparse parts as sparse? Same goes for "rbd clone", >>>> BTW. >>> >>> >>> Yep, this is in fact a bug. Opened http://tracker.ceph.com/issues/6257. >>> >>> Thanks! >>> sage > > _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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