[ovirt-users] import thin provisioned disks with image upload

[Gianluca Cecchi]

On Thu, Dec 7, 2017 at 9:33 PM, Nir Soffer <nsoffer at redhat.com> wrote:

>
> For transferring images over http, there is no way to avoid sending
> unused blocks, except compression.
>

OK, understood


>> Maybe this file was crated with preallocation=full?
>>>
>>
>> In virt-manager there is not this logic by default.
>> The default format is qcow2/sparse
>> When you create/add a disk you can choose "Select or create custom
>> storage":
>> https://drive.google.com/file/d/1gAwjAG5aRFC5fFgkoZXT5wINvQnov
>> 88p/view?usp=sharing
>>
>> And then choose a format between:
>> raw, qcow, qcow2, qed, vmdk, vpc, vdi
>>
>> In my case it was the default one, so qcow2, as qemu-img correctly
>> detects.
>>
>
> I tested creating qcow2 files with virt manager, and it seems to use
> the preallocation=metadata by default (behind your back), I guess
> for improving performance in some cases. oVirt doe not use this
> option so we don't have this issue when downloading files.
>
>
Ah, ok. I didn't know about this preallocation option of qemu-img
Does your example mean that by default oVirt uses preallocation=off when
creating thin provisoned disks?


> I hope I convinced you this time ;-)
>
> Nir
>

Yes :- ]  and thanks for the deep an detailed explanation, Nir

Thanks also to Eric for his comments in the other reply

Gianluca
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