|Subject:||Re: [Qemu-block] import thin provisioned disks with image upload|
|Date:||Thu, 07 Dec 2017 23:52:53 +0000|
On Thu, Dec 7, 2017 at 9:33 PM, Nir Soffer <address@hidden> wrote:For transferring images over http, there is no way to avoid sendingunused blocks, except compression.OK, understoodMaybe this file was crated with preallocation=full?In virt-manager there is not this logic by default.The default format is qcow2/sparseWhen you create/add a disk you can choose "Select or create custom storage":And then choose a format between:raw, qcow, qcow2, qed, vmdk, vpc, vdiIn 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 usethe preallocation=metadata by default (behind your back), I guessfor improving performance in some cases. oVirt doe not use thisoption so we don't have this issue when downloading files.Ah, ok. I didn't know about this preallocation option of qemu-imgDoes your example mean that by default oVirt uses preallocation=off when creating thin provisoned disks?
I hope I convinced you this time ;-)NirYes :- ] and thanks for the deep an detailed explanation, NirThanks also to Eric for his comments in the other replyGianluca
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