[CentOS] Utility to zero unused blocks on disk

Once upon a time, Greg Bailey <gbailey at lxpro.com> said:
> Wes didn't say the reason he wanted to zero unused blocks, but I
> always do this in kickstart scripts when constructing VM images as
> the image size is considerably reduced by doing this...

For that purpose, use something that can TRIM a VM image, like
virt-sparsify.
-- 
Chris Adams <linux at cmadams.net>