NonStop S-Series Planning and Configuration Guide (G06.25+)

Planning for System Availability and Support
HP NonStop S-Series Planning and Configuration Guide—523303-015
10-7
Calculating the Maximum Power-Fail Delay Time
Calculating the Maximum Power-Fail Delay Time
1. Software in each processor calculates a power-fail delay time using the following
information from the service processor:
•
The battery charge.
•
The hardware configuration of that group. The more components in the group,
the shorter the amount of time the batteries can power all the components.
The master service processors in group 01 receive information from the service
processors in all the other groups and use that information when calculating a
power-fail delay time.
2. The shortest power-fail delay time calculated by the processors is compared to the
configured maximum power-fail delay time, and the shorter of these two times is
the calculated maximum power-fail delay time for the system.
Configuring the Maximum Power-Fail Delay Time
The configured maximum power-fail delay time, in seconds, is set using the
POWERFAIL_DELAY_TIME attribute of the SCF Kernel subsystem.
Refer to the SCF Reference Manual for the Kernel Subsystem for information about
configuring the maximum power-fail delay time.
Battery Considerations
•
New systems are shipped with a default configured maximum power-fail delay time
of 30 seconds. Use SCF to configure this time to up to 50 seconds. However, the
actual, calculated maximum power-fail delay time for any group might be shorter
than 50 seconds, depending on the battery charge and hardware configuration for
that group.
•
Because the battery charge and hardware configuration for each group might be
different, each group in a system might have a different calculated maximum
power-fail delay time.
Note. The architectural maximum power-fail delay time is 300 seconds. SCF issues an
error message if you try to configure a larger value.
The functional maximum power-fail delay time, with current battery technology, is 50
seconds. If you attempt to configure a maximum power-fail delay time in the range 50
through 300 seconds, the system automatically limits it to the current functional maximum.