Re: [ovirt-users] preallocated storage issue?

Many thanks for the information and it does explain what I’m seeing. Is this the expected result though or is it a known bug? If using qemu-img to move images always results in a disk image that states it is preallocated but does not allocate the space, how do I move preallocated disk images? I know I can do the same within the VM and write a very large file full of zeros to grow the image to full capacity on disk but is that the correct approach? Thanks again, Simon *From:* Fred Rolland [mailto:frolland@redhat.com] *Sent:* Sunday, 7 August, 2016 10:55 *To:* Simon Barrett <Simon.Barrett(a)tradingscreen.com&gt; *Cc:* users(a)ovirt.org *Subject:* Re: [ovirt-users] preallocated storage issue? 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&gt; 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&gt; 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&gt; 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&gt; 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&gt; 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__ oVirt__prod__01/53560d43-874a-49c5-9c5a-8b90487c79f8/images/ d97f7706-3662-40bf-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 _______________________________________________ Users mailing list Users(a)ovirt.org http://lists.ovirt.org/mailman/listinfo/users