Re: [Qemu-devel] Wipe patch

[Brad Campbell <brad@wasp.net.au>]

ZIGLIO, Frediano, VF-IT wrote:
> Hi,
>   well, this is not a definitive patch but it works. The aim is to be
> able to wipe the disk without allocating entire space. When you wipe a
> disk the program fill disk with zero bytes so disk image increase to
> allocate all space. This just patch detect null byte writes and do not
> write all zero byte clusters.
> 

I've been giving this some pretty heavy testing over the last week and can say I've not noticed any 
negative performance impact or any other adverse side effects, not to mention the speedup when doing 
re-packing (which I do fairly regularly on both ext3 and ntfs guest filesystems).

While I'm here does anyone know of a simple program, either dos or linux based for wiping unused 
space on fat filesystems? The only ones I've found so far have been windows based.

This patch now conflicts pretty heavily with the new AIO changes it would seem. Further 
investigation required.

Ta,
Brad
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