[CentOS] Re: Torrent: reminder to use it folks!

Tom Diehl tdiehl at rogueind.com
Tue Dec 18 17:52:33 UTC 2007


On Mon, 17 Dec 2007, Kenneth Porter wrote:

> On Monday, December 17, 2007 7:05 PM -0800 Robert Arkiletian 
> <robark at gmail.com> wrote:
>
>> Also don't forget that many mirrors offer rsync. If you rename your
>> 5.0 DVD to the 5.1 version and do an rsync it will save lots of
>> bandwidth.
>
> That surprises me. Won't similar RPM's in the two images likely be at 
> different offsets in the iso? Can rsync deal with that? I didn't realize it 
> could handle shifted differences.

Rsync has no concept of the contents of files within an iso. It only knows
about blocks of data. Rsync is real good at fixing/updating iso's. It will only
transfer the blocks of data that have changed. Typically you get a large bandwidth
savings when using a previous iso as a seed. Just make sure you get the name correct
AND you do not abort the download midstream. If you abort the download midstream
rsync will delete your seed iso and leave you with whatever it has succeeded in
downloading and running a checksum against.

If you are really curious about all of this magic have a look here:
http://rsync.samba.org/how-rsync-works.html

Most people do not realize just how cool rsync is.

Hope this helps.

Regards,

-- 
Tom Diehl		tdiehl at rogueind.com		Spamtrap address mtd123 at rogueind.com



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