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Power Failures: Preparation and Recovery
HP Integrity NonStop NS-Series Operations Guide—529869-005
14-3
ESS Cabinets
During a power failure, a ServerNet/DA remains operational during the power-fail delay
time, but the external modular disk and tape subsystems attached to it do not. This
type of situation could result in data-integrity problems if the system software continues
processing data from an external disk drive or tape drive during a short power outage.
If a power failure occurs and the processors resume operations but one or more
external devices fail, data integrity problems can occur. The application programs must
be resilient to such device failures.
ESS Cabinets
ESS cabinets require a site UPS. ESS cabinets are not powered off programatically
with a power failure because they may be attached to other systems.
Air Conditioning
Unless the site UPS provides for maintaining air conditioning, it is possible that the
temperature could rise in the computer room complicating the ability of a system to
survive overheating before shutting itself down. For information about site overheating
problems, refer to the NonStop NS Series Site Preparation Guide.
Preparing for Power Failure
To prepare for power failures, set ride-through time, configure OSM power fail support,
and regularly monitor power supplies and batteries.
Set Ride-Through Time
Ensure that the system is set for the proper ride-through time. The default powerfail
delay time for NS-series systems that are configured with rack-mounted UPSs is 30
seconds. Contact HP Expert Services for the optimum ride-through time for your
system.
The ride-through time is set using the SCF commands to alter the
POWERFAIL_DELAY_TIME parameter. Refer to the SCF Reference Manual for the
Kernel Subsystem.
Configure OSM Power Fail Support
You must also configure OSM power fail support by performing a Configure Power
Source as UPS action for at least one processor switch power supply unit (for Integrity
NonStop NS16000 systems) or one IOAM or VIO power supply unit (for Integrity
NonStop NS14000 or NS1000 systems). Configuring at least one power supply as
being powered by UPS in the event of a power outage causes OSM to monitor a power
outage and, if the AC power is not restored before the specified ride-through time
period expires, OSM initiates an orderly system shutdown.
For more information, see the NonStop NSxxxx Hardware Installation Manual for your
Integrity NonStop NS16000, NS14000, or NS1000 server or the OSM Service
Connection User’s Guide.