backup and disaster recovery

[Tom Emerson]

On Tue, 29 Oct 2002, George Toft wrote:
> 
> I would try to be smart about what I mirror.  You don't need to copy a
> file that hasn't changed, so I would run find / -ctime -1 to get a list
> of files whose status has changed in the last day, and mirror those. 
> Next, you have to account for deleted files.  I can think of a few
> ways.  The one I used was running find periodically and using diff to
> see what is missing from the last time I ran it.  Delete those files.  I
> synced 4 servers every 20 minutes this way.  Fortunately, the
> filesystems were small so find didn't kill the system.

rsync -a --delete /from/stuff/ /to/mirror
or variations on this theme, read the man page & see 
http://www.rsync.org/  (from the SAMBA team).  rsync rocks.

I've rolled hourly server-to-server mirrors sorta like this:

rsync -a --delete  /from/here/ destination.server.tld:/to/mirror/dir

Best if you have a direct fast-ethernet or gigabit ethernet, but it works 
just fine coast-to-coast across disparate backbones too.

Your source host can have rsynd running (or available via xinetd and 
friends), with the rsyncd config file often here:  /etc/rsyncd.conf

Check the documentation and cruise google, rsync has been around quite a 
while and is very well documented.

 - t