[svlug] Backup strategies

Drew Bertola drew at drewb.com
Sat Oct 5 10:03:40 PDT 2002


On Sat, Oct 05, 2002 at 09:14:34AM -0700, Karen Shaeffer wrote:
> On Sat, Oct 05, 2002 at 08:39:49AM -0700, Drew Bertola wrote:
> > 
> > The point was that two spindles are good for even the simplest
> > scenario.
> 
> That was clear to me. But, the original question was concerned with backups.
> I think the central point of others, and certainly my comments, was that your
> solution has limitations that may be unacceptable to a large group of folks
> interested in backups.

Sorry, I only meant to suggest rsync rather than a commercial "wrapper
around tar" backup solution.  The examples were just there to
illustrate the ease with which a hobbiest could set up a backup
solution.

As far as two spindles on one machine vs. two machines, that was there
for the case of a home user who doesn't want to generate additional
heat / noise / space.  It's much more "environmentally friendly."

rsync is very versatile.  It can, as someone else stated, be used to
backup without deleting files that no longer exist locally (the
default).  It also can be used to create incremental updates of a
directory tree from a given date.  For example, I could do a complete
backup on Sunday (week 1), then incrementals throughout the week.  I
could then do the same for week 2.  That way, you not only have the
state of the machine at any point during the week.  

rsync has some great basic features:

- It compresses data during transit (by default), making it efficient
  over the network.

- It compares the state of every file between the working copy and the
  backup copy, thus it only updates files that have changed since the
  last backup.  This improves speed / network efficiency greatly.

- It plays well with ssh, so it's very secure over hostile networks
  (see: "-e ssh").

I typically do something like:

rsync -e ssh -avz drew at workstation.net:/home/drew drew at backup.net:/home

If I want to delete files that were deleted locally, I add --delete.

I can exclude files and directories using a stored list using:

--exclude-from=~/.rsync-excludes 

where:

$cat ~/.rsync-excludes
*~
*.rpm
*.tar
*.gz
*.tgz
*.tar.gz
*.zip
.ssh/
.bash_history
.rsync-exclude
weblogs/

And so much more.  rsync is very cool.

Just don't get src and dest confused.  That could be a bummer.  Think
of the cp command wrt src and dest.


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