12-05-2018
Here is my personal "power-loss-story" and it has nothing to do with a power-button:
Back around 2000 i was working for a data center, which - nothing really unusual - had a large ~1000hp diesel generator to back up its UPS. This diesel was tested every year once by switching it on for 2 minutes. Everything worked fine.
Now, what happens if you run such a system for two minutes a year? Disaster struck and showed to the responsible people exactly what happens in such a case: during a heavy thunderstorm the nearby transformer station (or, specifically, its large 6m-diameter capacitor was hit by a lightning. The whole area was suddenly without electrical current and the remains of the capacitor lay across half of the street in pieces not bigger than a few centimeters each.
First, our UPS kicked in - as planned. Then, when the UPS batteries went low, the diesel started. It ran for about 5-6 minutes, then stuck with a piston seizure because running keeps such a machine lubed. When it doesn't run all the bearings eventually run dry of oil. So far, so bad and our data center stood without electrical power.
What makes the story interesting, though, is: at the same time adear friend of mine (
shockneck) worked for another data center across the street. So, two days after the incident, we sat in a cafe commiserating about life as an admin. And he told me, they had a UPS, backed by a diesel. And because they knew that engines have to run every now and then to remain properly lubed they switched it on every month and let it run for 10 minutes. Alas, their diesel gave up a few minutes after starting. You know, when letting it run so often you need to refill the tank now and then.....
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LEARN ABOUT HPUX
power_onoff
power_onoff(1M) power_onoff(1M)
NAME
power_onoff - timed, automatic system power on, and power off
SYNOPSIS
time [date] ] time_designation]
DESCRIPTION
instructs the UPS monitor to shut down the system, and optionally informs the monitor when to power on the system again. The UPS monitor
in turn instructs the uninterruptible power source (UPS) when to turn the power off and on. The UPS monitor then proceeds to shut down the
system. The time to restart the system (power on) is specified with command-line arguments.
Some UPS units limit the time that can elapse between the time the power is turned off and the time it is turned back on. Please see your
UPS documentation for information about limitations.
requires a UPS that is supported by the UPS monitor (see ups_mond(1M)).
Command Line Arguments
The command has two forms, and recognizes the following arguments:
No power on.
Causes the system to be shutdown and not be powered back on.
time Can be specified as one, two, or four digits. One- and two-digit numbers represent hours; four digits represent hours and min-
utes. time can also be specified as two numbers separated by a colon single quote the letter "h" a period or comma A suffix or
can be appended. Otherwise a 24-hour clock time is understood. For example, and are read as 15 minutes after 8 in the morn-
ing. The suffixes and can be used to indicate Coordinated Universal Time. The special names and are also recognized.
date Can be specified as either a day of the week (fully spelled out or abbreviated) or a date consisting of a day, a month, and
optionally a year. The day and year fields must be numeric, and the month can be fully spelled out, abbreviated, or numeric.
These three fields can be in any order, and be separated by punctuation marks such as slash hyphen period or comma The years
00-68 would be interpreted as 2000-2068 and 69-99 would be 1969-1999. Two special ``days'', and are also recognized. If no
date is given, is assumed if the given time is greater than the current time; is assumed if it is less. If the given month is
less than the current month (and no year is given), next year is assumed.
or
If followed by a
time_designation of or lets the user startup the system when the specified time_designation has elapsed. A numerical operator,
enables the user to schedule the startup several hours, days, weeks, months, or years in advance (see EXAMPLES). Using the
argument is equivalent to using an increment of Both plural and singular forms of time_designation are accepted.
EXTERNAL INFLUENCES
International Code Set Support
Single- and multi-byte character code sets are supported.
RETURN VALUE
Exit code 0 is returned upon successful completion, otherwise non 0 is returned.
DIAGNOSTICS
issues diagnostic messages when it encounters syntax errors and out-of-range times.
EXAMPLES
To startup the system at 5:00 am next Tuesday, use
To startup the system at 5:30 am tomorrow, use
To make your system startup each weekday at 7:30 am and shutdown at 5:30 pm each week day, use to execute the first entry on Monday through
Thursday and the second entry on Friday (see crontab(1)).
To startup the system at 8:15 on January 24, use
To startup the system at 5:15 on January 24, use
To startup the system at 9:30 tomorrow, use
To startup the system 24 hours from now, use
To shutdown the system and not start it up, use
WARNINGS
Jobs can be submitted up to 2037. If jobs were submitted any later than 2037, an error message will display "BAD DATE".
Some UPS units limit the time that can elapse between the time the power is turned off and the time it is turned back on. Please see your
UPS documentation for information about limitations.
If the date argument begins with a number and the time argument is also numeric (and without suffix), the time argument should be a four-
digit number that can be correctly interpreted as hours and minutes.
Do not use both and within a single command; only the first operator is accepted and the trailing operator is ignored. No warning or error
is produced.
The power cord must be disconnected before servicing the unit.
AUTHOR
was developed by HP.
FILES
fifo for communicating with ups_mond.
SEE ALSO
at(1), cron(1M), crontab(1), queuedefs(4), proto(4), kill(1), sam(1M), ups_mond(1M).
power_onoff(1M)