[pve-devel] Proxmox VE 4.0 beta2 released!

Dietmar Maurer dietmar at proxmox.com
Thu Sep 10 17:05:50 CEST 2015

> qcow2, as a copy on write format, allows snapshots regardless of the 
> storage under it.

Yes, and this functionality is implemented in qemu. But you cannot make
snapshots when you use qemu-ndb (not supported by qemu-nbd).

> Also qcow2 is thin provisioned, that means it grows as you add data 
> (doesn't shrinks automatically) whereas with raw the whole image size 
> gets allocated on creation.

you can also create sparse 'raw' files.

> qcow2 has some overhead in comparison to raw.

and really much overhead if you use qemu-nbd.

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