DESCRIPTION
The
envd
daemon provides a means for the system to respond
to environmental conditions detected by hardware.
Such responses are typically designed to maintain
file system integrity and prevent data loss.
The environmental condition currently recognized by
envd
is over-temperature.
envd
logs messages and then executes actions when a supported
environmental event is detected.
Whether to do message logging and what actions to perform
for a given environmental event are determined by
configfile
(default is
/etc/envd.conf).
If no
-f
option was specified and the default configfile
/etc/envd.conf
does not exist,
envd
fails.
A recommended default
configfile
is available in
/usr/newconfig/etc/envd.conf.
The
configfile
(or
/etc/envd.conf)
is only examined when the daemon is started or when it receives a
SIGHUP
signal to restart and re-initialize the daemon itself.
envd
uses the
syslog
message logging facility to log warning messages.
If
configfile
specifies messages to be logged,
the destination of the warning messages
is determined by the configuration of the
LOG_DAEMON
facility of the
syslogd
daemon (see
syslogd(1M)
and
syslog(3C)
for details) and various
syslog
priorities defined below for the corresponding environmental events.
Warning messages are written to the console if
envd
is unable to send to
syslogd.
The
configfile
is composed of event lines,
each of which followed by zero or more action lines.
Comment lines can be interspersed at any point.
No more than one event line can be specified for a given event.
- Event
Event lines consist of an event keyword and a message indicator,
separated by a colon
(:).
Valid event keywords are
OVERTEMP_CRIT
and
OVERTEMP_EMERG.
Valid message indicators are
y
and
n.
An example is
OVERTEMP_EMERG:y,
indicating that warning messages are to be sent for the
OVERTEMP_EMERG
event.
Event keywords must start in the first column,
and only one event and one message indicator are allowed on a given line.
- Action
Action lines can consist of a sequence of any valid
/usr/bin/sh
commands or pipelines.
Lines from one event line to the next event line,
or to the end of the file,
are part of the action lines for the preceding event,
and are passed intact to the shell
to execute upon detecting the event.
The action for an event can span across several lines,
but the syntax of every line must be understood by
/usr/bin/sh.
There are no default actions for any events
if no action lines are specified.
No parsing or syntax checking is performed on the action lines;
system administrators are responsible
for verifying the correctness of the action syntax.
- Comments
Lines beginning with the
#
character in the first column are comment lines,
and all characters up to the subsequent new-line character are ignored.
Blank lines are ignored as comment lines.
Here is an example
/etc/envd.conf
file:
# The example below configures envd to log the warning message and
# to rcp critical applications to a remote machine at OVERTEMP_CRIT.
# It configures envd to log emergency messages and to perform
# system shutdown at OVERTEMP_EMERG, in order to preserve
# the data integrity.
OVERTEMP_CRIT:y
/usr/bin/rcp critical_appl_files \
remote_machine:/backup
OVERTEMP_EMERG:y
/usr/sbin/reboot -qh
Only users with appropriate privileges can invoke
envd.
Over-temperature Handling
Over-temperature handling is supported only on systems
equipped with over-temperature sensing hardware.
Over-temperature limits may vary, depending on the hardware.
Each system processor defines its own safest threshold
for supported equipment combinations.
The table below shows four levels of temperature states.
For the temperature range specific to your system configuration,
refer to any of the following documents for your system:
Site Planning and Preparation Guide,
Installation and Configuration Guide,
or
Operator Handbook.
The
syslog
priorities mapped to two over-temperature events are:
LOG_EMERG
(for
OVERTEMP_EMERG)
and
LOG_CRIT
(for
OVERTEMP_CRIT).
Any non-shutdown activities (e.g. file transfer) should be performed at
OVERTEMP_CRIT.
It is important to configure only critical activities for
OVERTEMP_CRIT
because the over-temperature might rise dramatically fast to
OVERTEMP_EMERG.
It is recommended to perform a quick shutdown using
/usr/sbin/reboot -qh
at
OVERTEMP_EMERG
to preserve file system data integrity.
If the hardware enters the
OVERTEMP_POWERLOSS
state and the system has not been shut down,
the sudden loss of power could result in data loss.
Note that power-fail recovery functionality is not available in this case.
When the hardware powers down, no warning messages are produced,
and no action is taken by the system.
Whenever the temperature rises from one level to another (such as from
NORMAL
to
OVERTEMP_CRIT
or from
OVERTEMP_CRIT
to
OVERTEMP_EMERG,
the warning message, if specified,
and the corresponding specified over-temperature action
is executed once, and only once, per state change.
Printable version
