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Operating Systems
HP-UX
MC ServiceGaurd
Post 4927 by alwayslearningunix on Friday 3rd of August 2001 05:23:39 PM
08-03-2001
MC ServiceGuard is still at the forefront of HP-UX's high availability software, it has been developed to the point where (providing hardware behaves itself) it can provide 99.999% availability when spreading a service across two service guarded machines.
It's quite a sophisticated product, providing a double heartbeat between nodes to monitor machine availability in a cluster and has a whole host of cluster wide and node specific configurable parameters - HP's course covers 5 days. It works from the entry level A class server through to the top end Superdome, as well as on workstations (although the reasoning behind it's application there would be somewhat baffling).
The product does not pretend to create fault tolerant machines, I think fault tolerance in the strict sense of the word is something yet to be attained on servers, and the domain of the mainframe - but it does guarantee high availibilty and with most service level agreements providing for scheduled maintenence downtime a high availability cluster that is service guarded can provide a near fault tolerant environment by allowing services to be flipped from node to node as the sectrions of the cluster is worked on for maintenance.
It's a great product, I would recommend learning it. I am on the course next week
Regards.
It's quite a sophisticated product, providing a double heartbeat between nodes to monitor machine availability in a cluster and has a whole host of cluster wide and node specific configurable parameters - HP's course covers 5 days. It works from the entry level A class server through to the top end Superdome, as well as on workstations (although the reasoning behind it's application there would be somewhat baffling).
The product does not pretend to create fault tolerant machines, I think fault tolerance in the strict sense of the word is something yet to be attained on servers, and the domain of the mainframe - but it does guarantee high availibilty and with most service level agreements providing for scheduled maintenence downtime a high availability cluster that is service guarded can provide a near fault tolerant environment by allowing services to be flipped from node to node as the sectrions of the cluster is worked on for maintenance.
It's a great product, I would recommend learning it. I am on the course next week
Regards.
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LEARN ABOUT REDHAT
starting
starting(7) Miscellaneous Information Manual starting(7) NAME
starting - event signalling that a job is starting SYNOPSIS
starting JOB=JOB INSTANCE=INSTANCE [ENV]... DESCRIPTION
The starting event is generated by the Upstart init(8) daemon when a new instance of a job begins starting. The JOB environment variable contains the job name, and the INSTANCE environment variable contains the instance name which will be empty for single-instance jobs. init(8) will wait for all services started by this event to be running, all tasks started by this event to have finished and all jobs stopped by this event to be stopped before allowing the job to continue starting. This allows jobs to effectively insert themselves as dependencies of other jobs. The event is typically combined with the stopped(7) event by services. Job configuration files may use the export stanza to export environment variables from their own environment into the starting event. See init(5) for more details. EXAMPLE
A service that wishes to be running whenever another service would be running, started before and stopped after it, might use: start on starting apache stop on stopped apache A task that must be run before another task or service is started might use: start on starting postgresql SEE ALSO
started(7) stopping(7) stopped(7) init(5) Upstart 2009-07-09 starting(7)