[ovirt-users] preallocated storage issue?

[Simon Barrett]

Another example. This one was moved to a new storage domain

root at ovirt_host1> qemu-img info dd6f25f6-7830-4024-915f-a20268797c34
image: dd6f25f6-7830-4024-915f-a20268797c34
file format: raw
virtual size: 200G (214748364800 bytes)
disk size: 5.0G

root@ ovirt_host1> cat dd6f25f6-7830-4024-915f-a20268797c34.meta
DOMAIN=53560d43-874a-49c5-9c5a-8b90487c79f8
VOLTYPE=LEAF
CTIME=1470305678
FORMAT=RAW
IMAGE=741976cd-d1cb-4031-bdbe-6a745dff16ef
DISKTYPE=2
PUUID=00000000-0000-0000-0000-000000000000
LEGALITY=LEGAL
MTIME=0
POOL_UUID=
SIZE=419430400
TYPE=PREALLOCATED
DESCRIPTION=
EOF


This one has not been moved:

root at ny2-lvb-066.mgt> qemu-img info 155f0d33-c280-4236-8d1e-fcb88f9a1242
image: 155f0d33-c280-4236-8d1e-fcb88f9a1242
file format: raw
virtual size: 90G (96636764160 bytes)
disk size: 90G

root at ny2-lvb-066.mgt> cat 155f0d33-c280-4236-8d1e-fcb88f9a1242.meta
DOMAIN=59bde2ff-e10d-477e-91c1-6355abff0999
CTIME=1464946639
FORMAT=RAW
DISKTYPE=2
LEGALITY=LEGAL
SIZE=188743680
VOLTYPE=LEAF
DESCRIPTION={"DiskAlias":"ny2-laa-010.prod_Disk1","DiskDescription":""}
IMAGE=82158182-81a4-458e-a41b-663756962666
PUUID=00000000-0000-0000-0000-000000000000
MTIME=0
POOL_UUID=
TYPE=PREALLOCATED
EOF

See the mismatch between "virtual size" and "disk size" on the one that was moved.

TIA,

Simon

From: users-bounces at ovirt.org [mailto:users-bounces at ovirt.org] On Behalf Of Simon Barrett
Sent: Friday, 5 August, 2016 10:25
To: users at ovirt.org
Subject: [ovirt-users] preallocated storage issue?

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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