Backup Central

I've just set up rdiff-backup to backup samba shares to a dedicated
failover machine. I'm thrilled. Our shares get backed up hourly now. But
I have a question about updated but unchanged files.

We use roaming profiles for our windows users so that they can log in
from different machines and see their familiar list of recent files, desktop
settings, etc. Every time a user logs on, their profile is copied to the
local machine. When they log off, it gets copied back. Typically, very
little has changed. But of course the time stamps are updated.

My question is this: would there be any benefit to using the
--no-compare-inode option? Would this decrease the number and size of files
generated? Is there any penalty such as a speed decrease when using this
option?

Or -- is there a way to tell rdiff to ignore changed file times if the
file is unchanged?

And finally -- does backing up a dir structure that has updated
modification times unnecessarily tax the server? Should I then maybe
exclude these directories during the hourly updates and just back them up
once a day?

Any feedback would be appreciated.

..Patrick

PS - I managed to get rdiff-backup going through an unencrypted link between
two computers with a private network connection using inetd and nc. Works
great. In case anyone has a secure link and feels that ssh just adds
overhead, I'd be happy to share the details of the setup.

On Sun, 02 May 2004 15:48:55 -0400
"Patrick J. Walsh" <pwalsh < at > dyna-q.com> wrote:

Any feedback would be appreciated.

A slightly different approach would be as outlined at
http://www.css.tayloru.edu/~nehresma/samba.html

Keith

--
----------------------------------------------------------------------
Small business computer support: http://www.tiger-computing.co.uk
Linux consultancy: http://www.TheLinuxConsultancy.co.uk
----------------------------------------------------------------------

A slightly different approach would be as outlined at
http://www.css.tayloru.edu/~nehresma/samba.html

I've seen that and we use some of those techniques. Particularly for
the My Documents directory. Log in and log out is pretty quick. But even
with that setup, profiles still need to be "roaming" and there are still
files copied back and forth with each login/logout, which leads me back to
my original question: what's the best say to use rdiff-backup with files
that may not change often, but have their last modification times changed
regularly, and possibly their inodes too.

Thanks for the pointer though.

..Patrick

"Patrick J. Walsh" <pwalsh < at > dyna-q.com>
wrote the following on Sun, 02 May 2004 15:48:55 -0400
We use roaming profiles for our windows users so that they can log in
from different machines and see their familiar list of recent files, desktop
settings, etc. Every time a user logs on, their profile is copied to the
local machine. When they log off, it gets copied back. Typically, very
little has changed. But of course the time stamps are updated.

My question is this: would there be any benefit to using the
--no-compare-inode option? Would this decrease the number and size of files
generated? Is there any penalty such as a speed decrease when using this
option?

Or -- is there a way to tell rdiff to ignore changed file times if the
file is unchanged?

And finally -- does backing up a dir structure that has updated
modification times unnecessarily tax the server? Should I then maybe
exclude these directories during the hourly updates and just back them up
once a day?

The --no-compare-inode option doesn't do what you hoped. There's no
option option to tell rdiff-backup to ignore files with changed times
if they are unchanged: rdiff-backup can only tell whether a file
with a changed time is changed by reading the file.

If a file's data doesn't change, the diffs produced will be very
small, and not take up much bandwidth. But reading the files and
producing/checking their signatures will take extra time.


--
Ben Escoto

The --no-compare-inode option doesn't do what you hoped. There's no
option option to tell rdiff-backup to ignore files with changed times
if they are unchanged: rdiff-backup can only tell whether a file
with a changed time is changed by reading the file.

Thank you for the explanation -- I had just about given up hope of
receiving one. I had set it up to back up profiles only once a day and, now
that this is clarified, I will leave it that way so as not to tax the
server.

Thanks again for the response,

..Patrick