primary backup configuration

[Gunther]

I setup MySQL one-way replication between the two MySQL servers. That means
both DB's are
always in sync, with the 2nd (and 3rd...) DB updated from the master.
As soon as you add another row into the db only in the secondary db, the
replication will stop updating
the secondary db.

I have two RADIUS Servers (with MySQL on the same server) at different
locations, but only 
allow access (via firewall) to the primary one. If the primary server is
down, I would have 
to open my firewall on the secondary server and the connected devices would
use the up-to-date db. 
When the primary server is back online, the firewall must immediately
disable any radius access. 
You can then setup the secondary DB as the master and primary as the slave,
synchonizing all 
radius entries, switch radius back to the first one and set the replication
back to the original state.
Most of this could probably fit into a few shell scripts doing the job more
automatically.

I know that my failover is not automatically, but I have not really found a
better way yet
with MySQL. Maybe Postgresql has better features.
The MySQL replication is so far (over 4 month) very reliable.

If both of your MySQL servers are on the same LAN you could also set up
'MySQL Cluster', which 
would make failovers automatically and there would be no manual intervention
required.
But apparently you cannot do that with servers connected over the Internet
as there is quite
a network load.

Gunther

> -----Original Message-----
> From: Maqbool Hashim
> Sent: Friday, March 17, 2006 1:38 PM
> I have two radius servers one primary and one backup one, on 
> different ip addresses.  They both have a mysql backend which 
> runs on the same physical machine.  I need the sql database 
> and radius configuration files to be synchronised 
> periodically (probably every 24hours).  I guess this is a 
> common setup, so I'd appreciate some ideas as to the best way 
> to achieve this?