>>These don't tell me much. Maybe it's better to show the actual commands and how >>you tell sparse from no sparse? Well, I create 2 empty source images files of 10G. (source.qcow2 and source.raw) then: du -sh source.qcow2 : 2M du -sh source.raw : 0M then I convert them with qemu-img convert : (source.qcow2 -> target.qcow2 , source.raw -> target.raw) du -sh target.qcow2 : 2M du -sh target.raw : 0M (So it's ok here) But If I convert them with drive-mirror: du -sh target.qcow2 : 11G du -sh target.raw : 11G I have also double check with #df, and I see space allocated on filesystem when using drive-mirror. I have the same behavior if target is a rbd storage. Also I have done test again ext3,ext4, and I see the same problem than with xfs. I'm pretty sure that drive-mirror copy zero block, qemu-img convert take around 2s to convert the empty file (because it's skipping zero block), and drive mirror take around 5min. ----- Mail original ----- De: "Fam Zheng" <famz@xxxxxxxxxx> À: "Alexandre DERUMIER" <aderumier@xxxxxxxxx> Cc: "qemu-devel" <qemu-devel@xxxxxxxxxx>, "Ceph Devel" <ceph-devel@xxxxxxxxxxxxxxx> Envoyé: Samedi 11 Octobre 2014 10:25:35 Objet: Re: [Qemu-devel] qemu drive-mirror to rbd storage : no sparse rbd image On Sat, 10/11 10:00, Alexandre DERUMIER wrote: > >>What is the source format? If the zero clusters are actually unallocated in the > >>source image, drive-mirror will not write those clusters either. I.e. with > >>"drive-mirror sync=top", both source and target should have the same "qemu-img > >>map" output. > > Thanks for your reply, > > I had tried drive mirror (sync=full) with > > raw file (sparse) -> rbd (no sparse) > rbd (sparse) -> rbd (no sparse) > raw file (sparse) -> qcow2 on ext4 (sparse) > rbd (sparse) -> raw on ext4 (sparse) > > Also I see that I have the same problem with target file format on xfs. > > raw file (sparse) -> qcow2 on xfs (no sparse) > rbd (sparse) -> raw on xfs (no sparse) > These don't tell me much. Maybe it's better to show the actual commands and how you tell sparse from no sparse? Does "qcow2 -> qcow2" work for you on xfs? > > I only have this problem with drive-mirror, qemu-img convert seem to simply skip zero blocks. > > > Or maybe this is because I'm using sync=full ? > > What is the difference between full and top ? > > ""sync": what parts of the disk image should be copied to the destination; > possibilities include "full" for all the disk, "top" for only the sectors > allocated in the topmost image". > > (what is topmost image ?) For "sync=top", only the clusters allocated in the image itself is copied; for "full", all those clusters allocated in the image itself, and its backing image, and it's backing's backing image, ..., are copied. The image itself, having a backing image or not, is called the topmost image. Fam -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
