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There is no HA mechanism built in the infrastructure for database HA. If a database instance or database fails, the monitoring tool will inform the operators about the failure, operators would then call the on call dba who will gauge the failure and take appropriate action. It's difficult to come with a time range for this action since it could vary based on type of failure. The options range from just restarting the instance to doing a database recovery from snapshot to getting storage and systems team involved.
Failure/Recovery:
| Type of Failure | Recovery |
|---|---|
| Disk Failure | Storage volumes are on RAID 6 redundant aggregates. They can tolerate up to 2 disk failures. |
| Netapp Head Failure | Secondary head takes over as primary and the transition happens in seconds transparent to the application |
| VM Host failure | VM ware moves the VM to a different host. This is cold failover but happens in seconds. |
| VM Host saturation | DRS moves the VM to a different VM host, transparent to the applications |
| VM network card failure | VM network connectivity is redundant, it can deal with single failures |
| Storage network card failure | Storage connection to the storage subnet is completely redundant. It can deal with single failure transparently. |
| Storage subnet | Storage subnet is completely redundant switched network. |
| Database instance failure | Recovery is manual, operators notice on the monitoring tool and then call the on call DBA |
| Database failure | Recovery is manual, operators notice on the monitoring tool and then call the on call DBA |