Re: [Qemu-devel] Wipe patch

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

andrzej zaborowski wrote:

>> I don't know if you mean just zeroing unused parts or reordering the
>> data and stuff like defragmentation. If you mean the former, there's a
>> universal method:
>>   dd if=/dev/zero of=xxx; rm xxx
>> where xxx is a path to a new file on the filesystem, which must be
>> mounted. It will creata a zero filled file there, which will fill all
>> availiable space, and remove the file afterwards. I used this when I
>> needed to send filesystem images through internet so that they
>> compressed well.
>> If you add dd=<a-big-number-here> it might take less time to write the 
>> file.
> Oops, I mean "bs=" ofcourse.

Yep, been doing similar, but the neato wipe programs generally also do cluster tails and unused 
directory entries and allow a really great compression ratio. Ta for the advice though.

Brad

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