Hello Sir,
We do not recommend customers to use only two servers for synchronization because if one server is down, all data will be centralized to the remaining server and if that server also fails then there will be data loss. If you still interested in using 2 servers for synchronization, please set the sync level to 0. We recommend you to have four servers and set the sync level to 25% to have each request sync with at least one other server. (And for three servers the sync level to 33%)
You can set the default sync level required in the validation server(s) but the clients can also tell the servers how much sync they require per request
For more information about the sync level, please refer the below link:
http://code.google.com/p/yubikey-val-server-php/Here are the step by step instructions to set the sync level.
1) SSH to the YubiRADIUS
2) Navigate to the location '/etc/ykval'
3) Open the ykval-config.php file
# vim ykval-config.php
4) Set the $baseParams['__YKVAL_SYNC_DEFAULT_LEVEL__'] value as per your requirement.
5) Save the file
6) restart the ykval sync service
/etc/init.d/ykval-queue restart
Hope this helps!
Thanks and best regards,
Samir.