Create a "hot backup" server machine?

[Doug Hardie]

On Sunday, Mar 30, 2003, at 14:18 US/Pacific, Ralph Dratman wrote:

> I'm trying to create an offsite "hot backup" of a FreeBSD server. If 
> the primary server fails, I want to transport the spare machine to the 
> existing site and bring it up as a replacement, with little or no 
> reconfiguration necessary.
>
> Nightly mirroring would be adequate in this situation. The system is 
> not running live transaction processing or anything comparable.
>
> Is there a straightforward, automated way to mirror a whole FreeBSD 
> system, using open source software?
>
> I'm testing ftpcopy to remotely mirror the files and directories. 
> Ftpcopy performs an incremental comparison using dates and file sizes, 
> which should minimize the nightly backup time and traffic load. So far 
> that part seems to be working well.
>
> But I haven't figured out how to get the users, groups and permissions 
> mirrored. There are about 200 users. And there may be other gotchas I 
> haven't thought of yet.

The approach I am using is to tar the system to a file on the 
production machine and then rsync that file with my off-site backup 
machine.  I leave it as a tar file on the backup as its almost 
impractical for me to move that machine to the production site.  I 
would replace the machine on the production site and then copy the file 
back from the backup machine and un-tar it.

In your case I would create the tar file, rsync it to the backup 
machine and then un-tar it there.  Tar retains permissions and 
ownership properly.  Leave the previous tar file on the backup machine 
as rsync will use it to reduce the download time.  My backup file (4 
servers) is just over 4 GB.  The rsync transfer only sends 1/16th of 
it.  Much of the archived data does not change very often.


-- Doug