designed to allow disk writes for items that are in transit through controllers and disks to
complete.
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 Hewlett Packard
Enterprise-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 a Hewlett Packard Enterprise-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
NS2100 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 a Hewlett Packard
Enterprise-supported UPS from the manufacturing default setting to an appropriate value for
your system. During installation of an NS2100 system or HPE UPS, your service provider can
refer to the "Setting the Ride-Through Time and Configuring for Maximized Runtime" procedure
in the
NS2100 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 HPE 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.
AC Power Monitoring
63
