[Info-vax] notification upon reboot

[Stephen Hoffman]

On 2013-02-28 08:48:14 +0000, Phillip Helbig---undress to reply said:

> In article <367e5873-e8ae-42a7-b35d-1d97f7dbdee3 at googlegroups.com>, Bob
> Gezelter <gezelter at rlgsc.com> writes:
> 
>> Within a cluster, there are two ways to detect node down directly:
>> 
>> - receive a copy of the OPCOM message reflecting node down
>> - use the Lock Manager to detect a node leaving the cluster (having a file
>> that is monopolizing a special file is implicitly relying on the Lock
>> Manager)
> 
> Perhaps more efficient: use F$CSID(CONTEXT) and F$GETSYI("NODENAME",,ID)
> in a loop to dynamically generate a list of nodes.

I'd agree that polling in a loop is a simple solution, but polling is 
not usually considered more efficient than receiving an asynchronous 
event notification.

The lock manager and OPCOM can both provide direct notifications, 
though an application might want ot use the $set_system_event system 
service.

If going to go to the effort to poll, then polling via SNMP can provide 
added details of what's going on, and can likely also detect cases 
where a node has crashed and returned entirely within a polling 
interval.  There are good network monitors available that already do 
this, such as Nagios, Xymon, etc.

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