[ovirt-users] preallocated storage issue?

[Simon Barrett]

If I create a preallocated disk for a VM, I see the disk image file listing as the size I requested (100G):

cd /rhev/data-center/mnt/storage_host1:_vol_pa1__nas__01b__oVirt__prod__01/53560d43-874a-49c5-9c5a-8b90487c79f8/images/d97f7706-3662-40bf-9358-80e0dc51bff4
root at ovirt_host> ls -l
total 105064644
-rw-rw---- 1 vdsm kvm 107374182400 Aug  5 10:57 75c14559-e18f-4cc8-a3fe-bc0de507720b
-rw-rw---- 1 vdsm kvm      1048576 Aug  5 10:57 75c14559-e18f-4cc8-a3fe-bc0de507720b.lease
-rw-r--r-- 1 vdsm kvm          313 Aug  5 10:57 75c14559-e18f-4cc8-a3fe-bc0de507720b.meta

and the corresponding space used on disk matches

root@ ovirt_host > du -sh *
101G    75c14559-e18f-4cc8-a3fe-bc0de507720b
1.1M    75c14559-e18f-4cc8-a3fe-bc0de507720b.lease
4.0K    75c14559-e18f-4cc8-a3fe-bc0de507720b.meta

If I then migrate that storage (while the VM is shutdown) to a new storage domain, the size on disk does not match the allocated size. In this case there is nothing in the disk yet so it shows as 0.

cd /rhev/data-center/mnt/storage_host2:_vol_pa1__ovirt__uatprod/1f2c2b48-1e77-4c98-a6da-5dc09b78cead/images/d97f7706-3662-40bf-9358-80e0dc51bff4
root@ ovirt_host> ls -l
total 1032
-rw-rw---- 1 vdsm kvm 107374182400 Aug  5 11:06 75c14559-e18f-4cc8-a3fe-bc0de507720b
-rw-rw---- 1 vdsm kvm      1048576 Aug  5 11:06 75c14559-e18f-4cc8-a3fe-bc0de507720b.lease
-rw-r--r-- 1 vdsm kvm          313 Aug  5 11:06 75c14559-e18f-4cc8-a3fe-bc0de507720b.meta

root@ ovirt_host > du -sh *
0       75c14559-e18f-4cc8-a3fe-bc0de507720b
1.1M    75c14559-e18f-4cc8-a3fe-bc0de507720b.lease
4.0K    75c14559-e18f-4cc8-a3fe-bc0de507720b.meta

oVirt still lists the disk as preallocated in the GUI but it is in fact thin provisioned.

I see the same issue if I clone a preallocated VM. The size on disk ends up being the equivalent of a thin-provisioned disk. I also had the issue when importing VM's from an export domain when I had selected preallocated in the import dialog box.

Is this a known issue? Should preallocated not mean preallocated on physical disk?

Ovirt Engine is running 3.6.4.1-1.el6

The ovirt nodes are running:

OS Version:                        RHEL - 7 - 2.1511.el7.centos.2.10
Kernel Version:                 3.10.0 - 327.4.5.el7.x86_64
KVM Version:                    2.3.0 - 31.el7_2.7.1
LIBVIRT Version:               libvirt-1.2.17-13.el7_2.2
VDSM Version:                 vdsm-4.17.23.2-0.el7.centos
SPICE Version:                  0.12.4 - 15.el7
GlusterFS Version:           [N/A]
CEPH Version:                   librbd1-0.80.7-3.el7

Many thanks,

Simon
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