Znyx Networks bh5700 manual Zdog

zdog

NAME

zdog - Configure and send heartbeats to watchdog enabled drivers.

SYNOPSIS

zdog [-d <level>] -h -i <interval> -n <heartbeats> zdog [-d <level>] -b

zdog [-d <level>] -a

DESCRIPTION

zdog is used to configure the base switch watchdog timer functions and to send heartbeats to the base switch watchdog drivers. There are two components to the base switch watchdog timer: A hardware component and a software component. The two components are independent from each other in implementation, but work together to provide safety against zombie hardware and software. The hardware component requires attention on a predefined 1.5 second interval. The driver acts on this at interrupt level to ensure that spurious reboots do not occur. The software component allows for a user programmable interval on which lack of application to driver communication will cause a reboot. Both components can be turned on with zdog.

The options -iand -nare used to configure the expected interval of heartbeats and the number of missed heartbeats of the software component before the base switch should be rebooted. If either the interval or number of heartbeats is 0, the software component is off. The -hoption is used to toggle on and off the hardware component of the watchdog timer. The hardware component is off by default.

Once the software component of the watchdog timer is turned on, a heartbeat must be sent with the -boption within that interval or the system will reboot. For example after issuing the following command:

zdog -i 5000 -n 3

A heartbeat must be sent at least every 3*5000=15000 milliseconds (every 15 seconds). This can be accomplished with something as simple as a polling script with a sleep, or started with a higher level function like monit. The driver checks for heartbeat timeout approximately 3 times per second. So (<heartbeat intervals>*<number of heartbeats>) faster then 330 milliseconds will have diminishing returns.

Combining monit and zdog allows multiple levels of insuring system integrity. The hardware component of zdog insures that the CPU is functioning well enough to execute something. The

Ethernet Switch Blade User's Guide release 3.2.2j page 286