How do i check the status of failover to make failover is correctly
These commands will give a good indicator of the status and configuration
show failover state
show running-config failover
Is there any downtime or small packet loss?
This depends on the type of traffic (Stateful/Non-Stateful), type of failover (Active/Active, Active/Standby, Cluster), type of failure (monitored interface down, hardware failure, flapping interface, etc), failover timers, and how modern the hardware is. I always recommend a maintenance window and prepare for unexpected downtime. Thorough testing will provide a baseline.
Cisco has some guidelines here:
How do i manually do failover instead of reload active device?
Force active status on standby unit:
Force standby status on active unit:
no failover active
Anything else i need to make sure before doing failover? like sync
config, connection etc?
Configurations should be sync'ed unless commands have been sent to the Secondary unit directly. If you suspect otherwise, a configuration comparison should be made. Some other recommendations are listed below. Ask any engineer and they will likely have additional recommendations.
- Verify current failover status using commands above
- Develop a thorough testing plan
- Adequate maintenance window
- Backup Configurations
- Write Running configurations to Start-up configurations
- Out-of-band Access
- Preemptive Cisco TAC case (very controversial among engineers and excessive IMHO)