[Users] Migrating from KVM to oVirt 3.1 fails - corrupt OVF

[Trey Dockendorf]

On Sun, Jul 22, 2012 at 3:20 PM, Ayal Baron <abaron at redhat.com> wrote:
> <SNIP>
>
>> >>
>> >>> Would a qcow2 image with preallocation=metadata be possible on an
>> >>> iSCSI data store?
>> >> ayal?
>> >>
>> > nope.  metadata preallocation means that each logical block has a
>> > corresponding physical block.
>> Ayal, by saying "logical block" and physical block here,  what do
>> they
>> stand for in linux systems?  I guess, physical block is "the scsi lun
>> disk", logical block is "lvm disk"? right?
>
> No, guest writing to block X, qcow maps X to Y on underlying device (e.g. LV)
> X is logical in example above.
> Y is 'physical'
>
> *Warning*, following explanation is a bit convoluted ;)
>
> Metadata preallocation means that all qcow clusters are already preset with every X mapped to a Y.
> Now on block storage, if guest writes to an X where X is mapped to Y which is beyond device size (because it's thinly provisioned), we would need to extend device to at least Y if not beyond.
> Worst case is if the guest I/O is to a block which is mapped to offset = size of virtual disk, which would force us to preallocate the entire disk at this point for a single block.
>
>
>>
>> > With files this is fine as you can seek wherever you want and the
>> > file will remain sparse.  With block devices this makes little
>> > sense as the second the guest accesses a block which is mapped to
>> > an unallocated physical block we'd have to allocate all the area
>> > up to that point.
>> > (btw, qemu-img will fail if you try to create such an image on a
>> > block device)
>> > _______________________________________________
>> > Users mailing list
>> > Users at ovirt.org
>> > http://lists.ovirt.org/mailman/listinfo/users
>> >
>>
>>
>> --
>> Shu Ming <shuming at linux.vnet.ibm.com>
>> IBM China Systems and Technology Laboratory
>>
>>
>>
> _______________________________________________
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> http://lists.ovirt.org/mailman/listinfo/users


Wanted to followup on this previous issue and report that after
upgrading to the stable release of 3.1, the import works.  What's
strange, is the latest attempt was using latest virt-v2v in EL6,
virt-v2v-0.8.7-6 , and when I went into the storage domain to view the
Imports it showed one of my past imports in the list that had failed
previously.  However it was fixed, it now works!

For all those wondering what steps I took to import a KVM VM into oVirt...

# virsh dumpxml dh-imager01 > dh-imager01.xml
(No editing of XML required now)
# virt-v2v -b ovirtmgmt -i libvirtxml -o rhev -os
dc-engine.tamu.edu:/exportdomain dh-imager01.xml

* From in the Engine Web interface go to the Export Domain's entry
under Storage Tab
* Select the VM Import tab
* Restore imported VM


Thanks
- Trey