Best practices for redundant servers

[Dennis Skinner]

Peter Nixon wrote:
> If you must use Mysql, use Master-Slave replication for as many authorization 
> servers as you wish, but configure only ONE radius server to actually write 
> accounting to the master database and all the others to use radrelay (or 
> radsqlrelay) to get the data to that server

We do something very much like this.  We have 2 sql modules setup in the
sql.conf file.  The authorize section lists sql2 and then sql1 within a
failover block and the accounting section only has sql1.

MySQL does have a clustering option:

http://www.mysql.com/products/database/cluster/

It has been a while since I read up on this, but I think it is fairly
complex and requires more than 2 database servers (I could be wrong).
In general I think it is overkill for a radius accounting situation.

For serious billable accounting you probably want to write to files and
then import them into the db (there is a module to help with this).
Radius will happily skip queries that take too long or if there are not
enough mysql connections available on the accounting side.

-- 
Dennis Skinner
Systems Administrator
BlueFrog Internet
http://www.bluefrog.com