[libvirt-users] Reintroduce "allocate entire disk" checkbox on virt-manager

[Gionatan Danti]

Il 26-06-2018 23:49 Cole Robinson ha scritto:
> I see it as another test case and larger UI surface in the common path
> for something that will save clicks for a corner case. I still don't 
> see
> it asworth exposing in the UI.
> 
> - Cole

I can not force this decision, obviously. However, let me recap why I 
found it important to have the "allocate disk now" checkbox:

- RAW files, even sparse one, are faster than Qcow2 files in the long 
run (ie: when block allocation is >8 GB);
- Qcow2 snapshots have significant gotchas (ie: the guest is suspended 
during the snapshot), while using RAW files will at least prevent using 
virt-manager snapshot feature without thinking;
- on CoW filesystems, using Qcow2 files will means *double* CoW with a) 
reduced performance and b) more wear on SSDs;
- on filesystems not supporting fallocate, libvirtd reverts to "write 
zeroes to the entire file) which is both a) very slow and b) detrimental 
to SSDs life;
- most other virtualization platform (old virt-manager and current oVirt 
included) split the choice of file format from the allocation policy.

I 100% agree that, using the custom disk creation mask, what I ask it 
entirely possible with virt-manager today. However, it would be *very* 
handy to have the checkbox back in the VM wizard itself.

Would opening a BZ ticket at least reopen the possibility to reconsider 
that decision?
Thanks anyway.

-- 
Danti Gionatan
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