Best practices for redundant servers

[Nicolas Baradakis]

Aaron Paetznick wrote:

> I've been struggling with this problem for a couple of weeks, and I 
> thought I'd pass it along to the mailing list.  Basically I'm trying to 
> answer the following question.  Given multiple identical dedicated 
> servers each running Linux and MySQL, how can I configure FreeRADIUS for 
> maximum stability, reliability, and performance?  The question, it 
> seems, is not as easy as is sounds.

I've already setup FreeRADIUS on multiple redundant servers, but never
had the time to write a HOWTO. The main guideline is:

1. Use LVS in a "direct routing" setup to dispatch the RADIUS requests.
   http://www.linuxvirtualserver.org/VS-DRouting.html

2. Use MySQL replication for the authorize database, so each FreeRADIUS
   server connects to a local, read only database.
   http://dev.mysql.com/doc/refman/5.1/en/replication.html

3. Use radsqlrelay for the accounting database, so the accounting data
   is written to a central database without slowing down the RADIUS
   servers. radsqlrelay is to be found in the FreeRADIUS source tarball,
   you could read the "rlm_sql_log" and "radsqlrelay" manpages for more
   details.

-- 
Nicolas Baradakis