NonStop NS2400 Series Planning Guide

and difficult than if all power failed and disk writes did not complete. The maximum ride-through
time for each system will vary, depending on system load, configuration, and the UPS capability.
Your rack-mounted HP UPS supplies power based on this ride-through time as long as the batteries
are fully charged. You must ensure that the battery capacity for a fully-powered system allows
enough time after OSM initiates the orderly shutdown to allow the disk cache to be flushed to
nonvolatile media.
NOTE: For details on the supported configurations for your HP UPS, including when the disk
drive cache option is enabled, refer to “Supported UPS Configurations” (page 189).
Also consider air conditioning failures during a real power failure because increased ambient
temperature typically causes the fans to run faster, which causes the system to draw more power.
By allowing for the maximum power consumption and applying those figures to the UPS calculations
provided in the UPS manuals, you can increase the ride-through time.
Guideline for Determining Ride-Through Time
A guideline for determining an appropriate ride-through time for your system is to use “Enclosure
Power Loads” (page 70) to calculate the maximum total rack power consumption for your system,
then find the estimated battery run time for that total using one of these documents:
• HP UPS Best Practices located at:
http://bizsupport2.austin.hp.com/bc/docs/support/SupportManual/c01788957/c01788957.pdf
• HP UPS R5000 User Guide located at:
http://h10032.www1.hp.com/ctg/Manual/c02945229.pdf
• HP UPS 3 Phase User Guide located at:
http://bizsupport2.austin.hp.com/bc/docs/support/SupportManual/c01079392/c01079392.pdf
The power failure time configured in SCF should be no more than 75 percent of the estimated
battery run time, converted to seconds.
Considerations for Site UPS Configurations
OSM cannot monitor a site UPS. The SCF configured ride-through time on a NonStop NS2400
series system has no effect if only a site UPS is used. With a site UPS instead of a rack-mounted
UPS, the customer must perform manual system shutdown if the backup generators cannot be
started.
It is also possible to have a rack-mounted UPS in addition to a site UPS. Since the site UPS can
supply a whole computer room or part of that room, including required cooling, from the perspective
of OSM, site UPS power can supply the group 100 AC power. The group 100 UPS power
configured in OSM, in this case, would still come from a rack-mounted UPS (one of the supported
models).
AC Power-Fail States
These states occur when a power failure occurs and an optional HP model R5000 or R12000/3
UPS is installed in each cabinet within the system:
DescriptionSystem State
NonStop operating system is running normally.NSK_RUNNING
OSM has detected a power failure and begins timing the outage. AC power
returning terminates RIDE_THRU and puts the operating system back into an
RIDE_THRU
NSK_RUNNING state. At the end of the predetermined RIDE_THRU time, if AC
has not returned, the system goes to POWER_OFF.
AC Power-Fail States 73