Re: [ovirt-users] Storage migration: Preallocation forced on destination

On 05/03/16 02:23, "Nir Soffer" <nsoffer(a)redhat.com&gt; wrote: >On Sat, Mar 5, 2016 at 12:19 AM, Pavel Gashev <Pax(a)acronis.com&gt; wrote: >> I think it's hard to calculate the additional space for cow format without analysing raw image. It's better to allocate enough space, and then decrease it after qemu-img convert. > >We use 10% as a rough estimate for additional space when converting >from raw to qcow format. Sure it will waste some space, but it is good >enough. > >How to you plan to check the used size on the destination lv? "qemu-img check" reports image end offset. Also it has --output=json option. # qemu-img check --output=json /rhev/data-center/00000002-0002-0002-0002-0000000002db/2e9250bd-5cf3-40c2-8e85-1e31d4c4d779/images/bc4c68be-0bb0-436a-b18d-014d9ae4e580/9b63d90e-cb1e-4a30-a0b6-0b80fa201f8d { "image-end-offset": 14648672256, "total-clusters": 524288, "check-errors": 0, "allocated-clusters": 223439, "filename": "/rhev/data-center/00000002-0002-0002-0002-0000000002db/2e9250bd-5cf3-40c2-8e85-1e31d4c4d779/images/bc4c68be-0bb0-436a-b18d-014d9ae4e580/9b63d90e-cb1e-4a30-a0b6-0b80fa201f8d", "format": "qcow2", "fragmented-clusters": 6 }

>> Also please consider qcow compat=1.1 as default disk format both for file and block storages. > >This will make your disk incompatible with old ovirt versions on el6. >In storage domain format v3 >we are using comapt=0.10. > >We plan to move to compat=1.1 in 4.0. Too long to wait :) Currently it's hardcoded. It would be great, if it was configurable via /etc/vdsm/vdsm.conf at least. It would allow early adopt compat=1.1 in el7 environments.