RE: [rdiff-backup-users] Quick question - Can rdiff (or anything else) do this?

[eharvey]

> Others have given links (and here's a good one:
> http://www.samba.org/rsync/how-rsync-works.html), but in a nutshell,
> Rsync will can the file at one end calculating checksums of blocks.
> At the other end, it will do a rolling checksum looking for matches -
> note that this is a rolling checksum so it will detect files that
> have had bits inserted or removed, thus altering the position of
> later data. It will then send the differences.
>
> Thus, if you take a 1GB file and add a single byte at the beginning,
> rsync will only have to send the checksums (and hashes used for
> verification) plus the first block - it will detect that the rest of
> the file has simply moved along a byte.
>
> Along with this, it can compress the data over the wire, use SSH to
> secure it, and even has the option to restrict bandwidth usage. Not
> only that, it runs multiple tasks in parallel - ie scans files
> looking for changes while still transferring earlier files. All this
> means that it is VERY effective over WAN links - like others, I've
> been using it for many years.
>
> You mentioned OS X. If you use the version of Rsync provided by
> Apple, then it's patched to handle HFS extended attributes if you
> specify -E or --extended-attributes as an option.



Hot damn.  I thought it just scanned for mtime etc.  For backing up my
parallels virtual hard drive, I'll go use simply rsync then...

Thanks...