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

[Nir Soffer]

On Fri, Dec 8, 2017 at 1:35 AM Gianluca Cecchi <gianluca.cecchi at gmail.com>
wrote:

> 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/1gAwjAG5aRFC5fFgkoZXT5wINvQnov88p/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?
>

Correct, we use the default.


>
>
>> 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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