[Users] Radius accounting: what happens if radius server is down?

[kjcsb]

I currently have (open)SER configured to write accounting records to a 
radius server. However there is a possibility that the Radius server may 
become unavailable. What is the recommended way to deal with this scenario? 
Is there a way to cache accounting records? Or is it best to write records 
to both flatfile and the radius server? Something like this:
modparam("acc", "db_flag", 1)
modparam("acc", "db_missed_flag", 3)
modparam("acc", "radius_config", "/etc/radiusclient-ng/radiusclient.conf")
modparam("acc", "radius_flag", 1)
modparam("acc", "radius_missed_flag", 3)

Any suggestions would be appreciated.

Regards

Cameron