[PATCH][RFC] space saving incrementals

[jw schultz]

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.


> 
> On Thu, Mar 07, 2002 at 01:25:50PM -0800, jw schultz wrote:
> > Please CC me directly as i'm not on the list.
> > 
> > I have attached a patch against latest CVS (cvs diff -u)
> > that adds the following functionality.  I can break it up if
> > you would prefer it in pieces.  Comments welcome.
> > 
> > 	o add compare-perms option
> > 		This creates a new inode for a file even if only
> > 		the perms have changed.  This way if a file
> > 		outside of destdir is hardlinked to a dentry
> > 		inside destdir the permissions (uid, gid,
> > 		mode) will be untouched preserving history
> > 		etc.
> > 
> > 	o link-dest option
> > 		After setting compare_dest this causes
> > 		unchanged files in destdir to be hardlinked
> > 		to link-dest.
> > 
> > 	o modified make_exclude_list to support stdin
> > 		if --exclude-from has argument of "-"
> > 		stdin will be read.
> > 		This lets us pipe a include/exclude list
> > 		into rsync so that we can generate it on the
> > 		fly.
> > 
> > The upshot of these is to allow rsync to make incremental
> > backups without modifying earlier versions but keep every
> > version as a complete tree.  It then becomes possible to
> > make tapes or restore from any image.
> > 
> > Although --compare-perms saves on block count this patch
> > only applies it to regular files so symlinks and device
> > nodes will still chew up inodes. :( 
> > 
> > for the sake of an example here is the command line i'm using:
> > 	/site/bin/rsync -v --stats -a -H -e ssh --compare-perms
> > 	    --delete --delete-excluded --numeric-ids --exclude-from -
> > 	    --link-dest /e/backup1/home/update1/tree leto:/efs/home/
> > 	    /e/backup1/home/update2/tree > /e/backup1/home/update2/log
> > 
> > i have tried to keep my changes small and consistent with the
> > existing coding style.  Feel free to dink with it.  I only
> > care about the performance.
> > 
> > 

-- 
________________________________________________________________
	J.W. Schultz            Pegasystems Technologies
	email address:		jw at pegasys.ws

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