6
Rev 1.3 • 25 Nov 14
NV9700
Discussion Points
Failure Detection
The NV9000 has an watchdog timer that can be used to detect failures of the NV9700. Its use is
optional. To enable the watchdog, create a registry entry:
\HKLM\SOFTWARE\NVISION/CTRLSYS/CONFIG/SerialWatchdogEnable
This entry is a
REG_DWORD
. Set its value to 1 to enable the watchdog and set its value to 0 to disable
the watchdog. The time-out period is 100 ms. If the NV9000 does not receive a status poll from the
NV9700 every 100 ms, it signals a fault condition.
Failure Conditions
The following table lists the causes of failure (the reasons for the red alarm light to go on).
Routers have their own system and power alarms.
Details
Although not exhaustive, these points provide some detail regarding system failures:
• Loss of communication between system controllers.
A communication link between the two system controllers is required. That link can be a cross-
over Ethernet cable, straight cables with an Ethernet switch, or a serial connection.
If the cabling is absent or broken, or if an Ethernet switch is present and it malfunctions, each
system controller begins to operate as a stand-alone controller and attempts to operate as the
active controller. Eventually, one or both system controllers will malfunction in this condition.
Both ‘Active’ LEDs of the NV9700 go on. Both ‘Alarm’ LEDs go on. If you see this condition,
reconnect or replace the crossover cable.
• Failed network connection (hub, switch, or NIC).
Condition
Failover?
Alarm?
Loss of communication between system controllers
No
a
a. Both system controllers go active.
Yes
Failed network connection (hub, switch, or NIC)
Yes
Yes
Active system controller failed
Yes
Yes
Inactive system controller failed
No
Yes
Lost contact with a router (all types)
Yes
Yes
Lost contact with a (configurable) number of control panels
Yes
Yes
Lost contact with third-party external interface
Not applicable
Solid state “hard drive” failed
b
b. A solid state “hard drive” contains the operating system as well as data. A standard hard disk contains data only.
Yes
Yes
(Spinning) hard disk failed
No
No
Lost 1 AC main or 1 power supply
No
No
Active system controller restarted
Yes
Yes
Inactive system controller restarted
No
Yes
Both system controllers restarted
Yes
Yes
Detection of system resource degradation
Yes
Yes
