The client has a system service availability requirement below. Originally, I was hoping we can run multiple Mango instances behind a load balancer like you were thinking, but this is not available yet. Can we come up with a fail-over design which we can quickly fail-over to a passive instance when the primary Mango instance goes down?
- System Service Availability
5.1 The service availability should meet 99.5% of the time, where "Service Availability" is defined as the total time in hours in a month for which the system can be connected and accessed, divided by the total service time in hours in a month (which is equal to the number of calendar days multiplied by 24 hours).
5.2 The maximum Down Time for the System per day should be 0.75 hour and the maximum Accumulated Down Time over a calendar month should be 3.65 hours where:
"Down Time" is defined as the period for which the System CANNOT be accessed, other than due to maintenance and /or upgrade carried out
"Accumulated Down Time" is defined as the accumulated number of hours of down time in a calendar month. This number will be reset to zero at the beginning of each calendar month
5.3 The maintenance window shall be agreed with the Employer after project commencement. Normally it shall be aligned with non-traffic hour of the Station.