[PATCH][RFC] space saving incrementals

[Dave Dykstra]

On Mon, Mar 11, 2002 at 11:32:11AM -0800, jw schultz wrote:
> On Mon, Mar 11, 2002 at 12:41:07PM -0600, Dave Dykstra wrote:
> > On Fri, Mar 08, 2002 at 03:05:14PM -0800, jw schultz wrote:
> > > On Fri, Mar 08, 2002 at 03:45:04PM -0600, Dave Dykstra wrote:
> > > > I like link-dest, and the "-" for exclude-from/include-from was already
> > > > something I was planning to add one of these days along with the
> > > > --files-from option I still plan to write, but --compare-perms confuses
> > > > me.  Can you give examples of when you need it?
> > > > 
> > > > - Dave Dykstra
> > > 
> > > sequence of commands:
> > > 	admin# rsync /project /vault/monday
> > > 	admin# chmod 666 /project/somefile
> > > 	admin# chown bin /project/someotherfile
> > > 	admin# rsync --link-dest=/vault/monday /project /vault/tuesday
> > > 
> > > Now /vault/monday/somefile has perms of 666 and
> > > someotherfile is owned by bin.  I cannot restore the perms
> > > from /vault/monday.  That info is lost. /vault/monday no
> > > longer is an accurate representative of what existed when it
> > > was created.
> > > 
> > > With --compare-perms somefile and someotherfile will not be
> > > linked between monday and tuesday even though the contents
> > > haven't changed.
> > > 
> > > compare-perms only makes sense when you are using link-dest.
> > 
> > 
> > Why not just always do --compare-perms functionality with --link-dest?  I'd
> > rather not have more hard-to-explain options if they can be avoided.
> > 
> > - Dave Dykstra
> 
> I personally wouldn't mind.  --compare-perms existed before
> --link-dest.  I started by doing a cp -al before the rsync
> but that seemed wastefull especially with how little it took
> to add the --link-dest onto --compare-dest.
> 
> However, i suspect that some others would gripe at rsync
> --link-dest not linking if all that changed was file
> meta-data.

I can't imagine anybody griping at that.

> I could be wrong but i think --link-dest without
> a seperate --compare-perms or its inverse might cause more
> confusion although users could leave off -pgo if they don't
> care about the meta-data.

Right.


> This may become more of an issue with ACLs and other
> extended file attributes.  But that is at least another year
> in the future.
> 
> By the way, really appreciate rsync.  I tried this with
> rdist because it didn't have the permissions problem but the
> performnce stank.  Monitoring it i found the slowdown wasn't
> bandwith, disk or CPU.  Rsync even did the initial transfer
> (nothing on dest) at over 10x the speed with the limitation
> being the 350MHz cpu on the backup server.


- Dave Dykstra