[pve-devel] [PATCH storage 1/1] fix #3580: plugins: make preallocation mode selectable for qcow2 and raw images

Thomas Lamprecht t.lamprecht at proxmox.com
Thu Sep 9 14:28:40 CEST 2021

On 09.09.21 14:04, Fabian Ebner wrote:
> Am 09.09.21 um 13:11 schrieb Lorenz Stechauner:
>> On 09.09.21 12:25, Fabian Ebner wrote:
>>> Am 08.09.21 um 10:11 schrieb alexandre derumier:
>>>> Hi,
>>>> it can be done too with ceph rbd with "rbd create ... –thick-provision"
>>> Hi,
>>> there also is the 'sparse' storage config option (currently only used for ZFS plugins). If there is only thick or thin, re-using that one is probably nicer, because the newly proposed preallocation option seems to be closely tied to qemu-img.
>> Sounds like a good idea. I doubt, that anyone would use full prellocation anyway, so simply using 'sparse' for prealloc=off and default remains prealloc=metadata sounds good.
> I actually only meant re-using 'sparse' for the RBD use case. But yes, it seems like re-using it for the qemu-img use case would be enough to fix the bug too. It might be a bit confusing though, because when sparse is not set, the images would still be mostly sparse (except for metadata).

Yeah, I'm not sure that just deriving all from the sparse storage option would
be good UX - I think it should be per creation and if we want to expand the scope
of such a value we should rather see it as fallback.

But IMO this is a bit of an edge case anyway, so I'd not rush the latter without
user demand.

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