Re: [CentOS-virt] compress raw image

Rainer Traut wrote:

Am 08.08.2011 18:51, schrieb Momo:

...

Hi

No, he's talking filling with zeros unused blocks. That's a prerequisite
to optimize for a sparse image _on the other side_ and/or compression
during the transfer.

I know of an ext2/3/4 utility that does precisely that. I have no idea
if such an utility exists for NTFS.

It exists for NTFS, have a look at "sdelete.exe" with -c option.

Sorry for getting back so late.

Yes, guys, exactly what I meant was filling unused space with zeros. The linux tools to compress and transfer cannot read the ntfs data structure and compress every garbage. But if unused blocks are filled with zeros one can achieve much better compression.

I looked into sdelete.exe, this really is helpful but obviously works in running instance.

My idea is to mount the raw image with ntfs3g and create a big file with zeros. This should be sufficient, like Marco said.

Regards, Rainer

Don't forget rsync's parms --bwlimit=0 --compress-level=1