[Linux-HA] HA Stats

[Hari]

Hi,
  I recently joined this group. Iam working on a HA project for wireless
controller.
 We are looking at different options. I just wanted to know how is the linux
HA implemented and some statistical information ...
1) How is the heartbeat implemented?
2) What is the retry mechanism used?
3) What are the different timer values used in this solution?
4) What are the performance stats (like switchover time in different
scenarios)?

Please guide in this.
Let me know if there are any documents/links related to this.

Thanks & Regards,
Srihari.