Communicator e3000 MPE/iX Release 7.5 (Software Release C.75.00) (30216-90336)

Chapter 5
Technical Articles
UPS Monitor/iX and UPSUTIL Enhancements
113
UPS Monitor/iX and UPSUTIL Enhancements
By Bob Berliner — Commercial Systems Division
Introduction
In response to user community requests, the UPS Monitor/iX subsystem of MPE/iX has been enhanced in
Release 7.5 to provide new capabilities related to the system’s handling of AC power failures at UPS devices.
The UPSUTIL utility program for UPS subsystem management has been correspondingly enhanced to support
the new features of UPS Monitor/iX.
UPS Monitor Enhancements
New UPS subsystem configuration options have been added to the UPS Monitor’s configuration file facility.
The new options permit users (System Managers) to specify and make use of a custom-tailored MPE/iX
Command File to control the HP e3000 system’s behavior in the event of a UPS-device-detected AC power
failure lasting longer than a user-specified amount of time.
The primary benefit of this “powerfail command file” enhancement is that it can be used in conjunction with
another Release 7.5 enhancement, the new CI-based “:shutdown” command, to cause an orderly system
shutdown when the system is notified of a UPS-detected power failure. (For information about the new
“:shutdown” command, see the SHUTDOWN: NEW CI COMMAND article elsewhere in this Release 7.5
Communicator.)
One of the new configuration options specifies the amount of time (called the “powerfail grace period”) that a
power failure must last in order for the UPS Monitor to cause the user’s “powerfail command file” to begin
execution.
Another new option allows the user to specify, by its file name, the particular MPE/iX command file to execute
in response to a power failure that meets the “grace period” time duration specification.
A third new configuration option allows a System Manager to override the standard behavior of the UPS
Monitor subsystem in case of a power failure that nearly exhausts a UPS device’s battery backup power
capacity. Normally, the UPS Monitor intentionally causes a special System Abort in case of a “low battery
charge” condition reported from a UPS device. The reason for this is to ensure that no disk device is in the
midst of writing data to the disk surface at the time at which the disk device actually loses its AC power,
because modern SCSI disk devices are susceptible to writing garbled data if they are performing a write
operation when power disappears. To prevent this possibility, the UPS Monitor aborts the running system
ahead of UPS battery exhaustion time, so that existing disk write operations either complete or abort
(harmlessly), and no new disk write operations are started, prior to the time when a disk device actually loses
its power. The new configuration option allows a brave-hearted and insistent HP e3000 System Manager, who
strongly believes that she/he can manage the disk situation effectively by other means, to prevent this
intentional system abort, and allow the HP e3000 system to “keep running” even after a UPS device has
announced “low battery charge — approximately two minutes of power remaining”.
NOTE Use of this “keep running” option is entirely at the discretion and responsibility of the HP3000
System Manager. Hewlett-Packard DOES NOT RECOMMEND the use of this option, and can
not assure users that disk-stored data will not be corrupted if this option is used.