Re: [rdiff-backup-users] Why do I see a huge variation in the time rdiff-backup takes?

[Adrian Klaver]

On 03/31/2015 03:37 PM, Segundo Bob wrote:
> On 03/30/2015 07:39 PM, Robert Nichols wrote:
> > Any change in the recorded metadata for a file will cause rdiff-backup
> > to do a time-consuming diff of the old and new files. For files with
> > just a single link, that data includes ModTime, Uid, Uname, Gid, Gname,
> > and Permissions.
>
> Thank you.  I think this explains why rdiff-backup mistakenly thought
> that 98.7% of my files had been changed.
>
> Between 2015-03-22 Sun and 2015-03-29 Sun, I switched from Xubuntu32
> 12.04 to Xubuntu64 14.04.  Below I list the file uid, uname, gid, and
> gname for about 98.7% of the files backed up in each rdiff-backup run:
>
> Xubuntu32 12.04
>      uid 1000
>      uname bob05
>      gid 1000
>      gname bob05
>
> Xubuntu64 14:04
>      uid 1000
>      uname bob06
>      gid 1000
>      gname bob06
>
> That is, the uname and gname changed for 98.7% of the files.  This
> caused rdiff-backup to needlessly compare 98.7% of the files and to find
> very few of them changed.
>
> Perhaps uname and gname should not be included in the metadata?  They
> are not part of the data stored in the file or the file's directory entry.

http://www.nongnu.org/rdiff-backup/rdiff-backup.1.html

--preserve-numerical-ids
              If  set,  rdiff-backup will preserve uids/gids instead of 
trying
              to preserve unames and gnames.  See the USERS AND GROUPS 
section
              for more information.

I would also read the USERS AND GROUPS section for the caveats and other 
ways to deal with this.

> In the future, I will start a new archive file whenever I change from
> one system-boot to another, if my uname or gname differs between the two
> systems.
>
> Thank you very much for your help.


--
Adrian Klaver
address@hidden