NonStop NS2200 Series Planning Guide

NOTE: Do not turn off the UPS as soon as the NonStop OS is down. The UPS continues to supply
power until that supply is exhausted, and that time needs to be long enough for disk controllers
and disks to complete disk writes.
If a user-supplied rack-mounted UPS or a site UPS is used rather than the HP-supported UPS models
mentioned above, the system is not notified of the power outage. The user is responsible for
detecting power transients and outages and developing the appropriate actions, which might
include a ride-through time based on the capacity of the site UPS and the power demands made
on that UPS.
The UPS and ERMs installed in modular cabinets do not support any devices that are external to
the cabinets. External devices can include tape drives, external disk drives, LAN routers, and
SWAN concentrators. Any external peripheral devices that do not have UPS support will fail
immediately at the onset of a power failure. Plan for UPS support of any external peripheral devices
that must remain operational as system resources. This support can come from a site UPS or
individual units as necessary.
NOTE: OSM does not make dynamic computations based on remaining capacity of the
rack-mounted UPS. The ride-through time is statically configured in SCF for OSM use. For example,
when power comes back before the initiated shutdown, but then fails again shortly afterward, the
UPS has been depleted by some amount and does not last for the ride-through time until it is fully
recharged. OSM does not account for multiple power failures that occur within the recharge time
of the rack-mounted UPS.
This information relates to handling power failures:
• To set the ride-through time for an HP-supported UPS from the manufacturing default setting
to an appropriate value for your system, your service provider can refer to the "Setting the
Ride-Through Time and Configuring for Maximized Runtime" procedure in the NonStop
NS2200 Hardware Installation Manual.
• To set ride-through time using SCF, see the SCF Reference Manual for the Kernel Subsystem.
• For the TACL SETTIME command, see the TACL Reference Manual.
• To set system time programmatically, see the Guardian Procedure Calls Reference Manual.
Considerations for Ride-Through Time Configuration
IMPORTANT: You must change the ride-through time for an HP-supported UPS from the
manufacturing default setting to an appropriate value for your system. During installation of a
NonStop NS2200 system or HP UPS, your service provider can refer to the "Setting the Ride-Through
Time and Configuring for Maximized Runtime" procedure in the NonStop NS2200 Hardware
Installation Manual for these instructions.
The goal in configuring the ride-through time is to allow the maximum time for power to be restored
while at the same time allowing sufficient time for completion of disk writes for IOs that passed to
the disk controllers before ServerNet was shut down. Allowing enough time for sufficient completion
of these tasks allows for a relatively clean shutdown from which TMF recovery is less time-consuming
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 198).
76 System Installation Specifications for NonStop NS2200 Systems