4:55 a.m.
Simon,
What is happening is that when we create a preallocated disk on NFS, we
fill the file with zeros in order to "allocate" the space.
However, while copying the disk we use qemu-img that will ignore the zeros.
Quick way to demonstrate:
[root@white-vdsd test]# dd if=/dev/zero of=myfile.txt bs=1M count=1
1+0 records in
1+0 records out
1048576 bytes (1.0 MB, 1.0 MiB) copied, 0.00172084 s, 609 MB/s
[root@white-vdsd test]# du -h myfile.txt
1.0M myfile.txt
[root@white-vdsd test]# ls -lh myfile.txt
-rw-r--r-- 1 root root 1.0M Aug 7 12:39 myfile.txt
[root@white-vdsd test]# qemu-img convert myfile.txt myfile2.txt
[root@white-vdsd test]# ls -lh myfile2.txt
-rw-r--r-- 1 root root 1.0M Aug 7 12:41 myfile2.txt
[root@white-vdsd test]# du -h myfile2.txt
0 myfile2.txt
[root@white-vdsd test]# qemu-img info myfile.txt
image: myfile.txt
file format: raw
virtual size: 1.0M (1048576 bytes)
disk size: 1.0M
[root@white-vdsd test]# qemu-img info myfile2.txt
image: myfile2.txt
file format: raw
virtual size: 1.0M (1048576 bytes)
disk size: 0
I hope this explains what you see.
Regards,
Fred
On Sun, Aug 7, 2016 at 11:13 AM, Simon Barrett <
Simon.Barrett(a)tradingscreen.com> wrote:
Storage is NFS. What logs would you like to see?
Many thanks.
Simon
On Sun, Aug 7, 2016 at 8:53 AM +0100, "Fred Rolland"
<frolland(a)redhat.com>
wrote:
Simon hi,
What storage type are you using in source and target storage domains ?
(NFS, ISCSI....)
Can you share the logs?
Thanks,
Fred
On Fri, Aug 5, 2016 at 6:37 PM, Simon Barrett <
Simon.Barrett(a)tradingscreen.com> wrote:
> Another example. This one was moved to a new storage domain
>
>
>
> root@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(a)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(a)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(a)ovirt.org [mailto:users-bounces@ovirt.org] *On
> Behalf Of *Simon Barrett
> *Sent:* Friday, 5 August, 2016 10:25
> *To:* users(a)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__oVir
> t__prod__01/53560d43-874a-49c5-9c5a-8b90487c79f8/images/d97f
> 7706-3662-40bf-9358-80e0dc51bff4
>
> root@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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>
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