Hi Ceph uses thin-provisioning so it will not allocate the full block device when you create it with qemu-img.
When you write to the data it then allocates the block devices. However, you can enable TRIM/DISCARD in the VM as per the documentation here: http://ceph.com/docs/next/rbd/qemu-rbd/ - this should allow ceph to reclaim the deleted space. Regards -- Brad. On 10 January 2014 09:21, lyz_pro <lyz_...@163.com> wrote: > Hi > I have a question: > I used qemu-img create a rbd disk. and attach it to a vm. > then I format the disk as ext3 and mount the disk in vm. > After above steps, > I dd a 1G file to the rbd disk in vm. then remove the disk, > and dd a 1G file again, then remove it. do this several times. > > I use `watch ceph -s` during dd operation and found the used space in ceph > cluster is always increase, > and not found decrease. > > The above condition make me confuse, Is there any one could kindly explan > why this happened , is there somthing I miss ? > > additional: > The qemu and libvirt version I use is : > Compiled against library: libvirt 0.10.2 > Using library: libvirt 0.10.2 > Using API: QEMU 0.10.2 > Running hypervisor: QEMU 0.12.1 > > ceph-0.72.2-0.el6.x86_64 > qemu-img-0.12.1.2-2.415.el6.3ceph.x86_64 > qemu-kvm-tools-0.12.1.2-2.415.el6.3ceph.x86_64 > > > > -------------- > lyz_pro > 2014-01-10 > > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >
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