Prior to the actual update, health checks are performed automatically when an update is started. If an update health check fails, it can cause an update to abort (see following example). Update health checks only validate issues that can impact updates.
Figure 96 Example BUI and CLI Update Health Checks Failures
hostname:maintenance system updates ak-nas@2013.06.05.0.0,1-1.6> upgrade This procedure will consume several minutes and requires a system reboot upon successful update, but can be aborted with [Control-C] at any time prior to reboot. A health check will validate system readiness before an update is attempted, and may also be executed independently using the check command. Are you sure? (Y/N) error: System is not in an upgradeable state: prerequisite healthcheck reports problems. See alert log for more.