Re: Zeroing unused FFS blocks

[Curt Sampson <cjs%netbsd.org@localhost>]

On 2008-01-25 13:29 +0200 (Fri), Martti Kuparinen wrote:

> Now, after halting the domU it would be very nice to compress this virtual 
> hard drive before storing it on a DVD or moving it to another server.
>
> Is there any way to zero all unused FFS blocks in order to make the 
> compressed image smaller?

If you're going to process the file anyway, before storing it or moving it,
my recommendation would be:

    dump -0 -a -F /path/to/fs/image -f - | gzip > image.dump.gz

cjs
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