RCMSCRIPT(4)RCMSCRIPT(4)NAMErcmscript - script interface specification for the Reconfiguration and
Coordination Manager
SYNOPSIS
rcm_scriptname scriptinfo
rcm_scriptname register
rcm_scriptname resourceinfo resourcename
rcm_scriptname queryremove resourcename
rcm_scriptname preremove resourcename
rcm_scriptname postremove resourcename
rcm_scriptname undoremove resourcename
DESCRIPTION
Reconfiguration and Coordination Manager (RCM) is a framework designed
to coordinate device consumers during Solaris Dynamic Reconfiguration
(DR). The interfaces specified in this man page allow device consumers,
such as application vendors or site administrators, to act before and
after DR operations take place by providing RCM scripts. You can write
your own RCM scripts to shut down your applications, or to cleanly
release the devices from your applications during dynamic remove opera‐
tions.
An RCM script is an executable perl script, a shell script or a binary.
Perl is the recommended language. Each script is run in its own address
space using the user-id of the script file owner.
An RCM script is invoked on demand in response to DR as follows:
<scriptname> <command> [args ...]
Every script must implement the following RCM commands:
scriptinfo
Get script information.
register
Register devices the script handles.
resourceinfo
Get resource information.
A script might include some or all the of the following commands:
queryremove
Queries whether the resource can be released.
preremove
Releases the resource.
postremove
Provides post-resource removal notification.
undoremove
Undo the actions done in preremove.
When a script's register command is run, the script should supply, in
return data, all resource names the script or its application handles
that could potentially be removed by DR. A resource name refers to a
name in /dev path name.
Below is a high-level overview of the sequence of script invocations
that occurs when dynamic removal of a script's registered resource is
attempted. See the COMMANDS section for a detailed description of the
commands.
1. Prior to removing the resource from the system during DR,
the script's queryremove command is run:
<scriptname> queryremove <resourcename>
The script should check for obvious reasons why the resource
can not be removed from the perspective of its service or
application.
2. If the script indicates that the resource can be removed in
the queryremove command. The script's preremove command is
run:
<scriptname> preremove <resourcename>
The script releases the resource from the service or appli‐
cation represented by the script and prepares for the
resource removal. Releasing the resource includes closing
the resource if the resource is currently opened by its
application.
3. The system then proceeds to remove the resource.
4. If the system has removed the resource successfully the
script's postremove command is run:
<scriptname> postremove <resourcename>
Otherwise the script's undoremove command is run:
<scriptname> undoremove <resourcename>
For any commands the script does not implement, it must exit with exit
status of 2. RCM silently returns success for the script's unimple‐
mented commands.
A script performs the following basic steps:
o Takes RCM command and additional arguments from the command
line and environment parameters.
o Processes the command.
o Writes the expected return data to stdout as name=value
pairs delimited by newlines, where name is the name of the
return data item that RCM expects and value is the value
associated with the data item.
Environment
The initial environment of RCM scripts is set as follows:
o Process UID is set to the UID of the script.
o Process GID is set to the GID of the script.
o PATH variable is set to /usr/sbin:/usr/bin.
o Current working directory is set to:
o /var/run for scripts owned by root
o /tmp for scripts not owned by root
o File descriptor 0 (stdin) is set to /dev/null
o Environment variable RCM_ENV_DEBUG_LEVEL is set to the debug
level. Logging is discussed below.
o
The following environment variables are also set where pos‐
sible:
o LANG
o LC_COLLATE
o LC_CTYPE
o LC_MESSAGES
o LC_MONETARY
o LC_NUMERIC
o LC_TIME
o LC_ALL
o TZ
See environ(5) for a description of these variables. See gettext(1)
for details on retrieving localized messages.
All environment variable names beginning with RCM_ENV_ are reserved for
use by the RCM.
The character encoding used by the RCM and RCM scripts to exchange RCM
commands, environment parameters, and name-value pairs is ASCII unless
the controlling environment variables are specified otherwise.
Commands
scriptinfo
The scriptinfo command is invoked to gather information about the
script.
Return data:
If successful, the script must write the following
name-value pairs to stdout and exit with status 0:
o rcm_script_version=1
o rcm_script_func_info=script_func_info
o rcm_cmd_timeout=command_timeout_value
where script_func_info is a localized human-readable
message describing the functionality of the script.
The RCM monitors the execution time of RCM commands by
RCM scripts. command_timeout_value is the maximum time
in seconds the script is expected to take to process
any RCM command except the scriptinfo command itself.
If an RCM script does not process the RCM command and
exit within this time, RCM sends a SIGABRT signal to
the script process. RCM then waits for a few seconds
for the script to finish the processing of the current
RCM command and exit. If the script does not exit
within this time, RCM sends a SIGKILL signal to the
script.
The rcm_cmd_timeout name-value pair is optional. It is
only needed if the script is expected to take more than
a few seconds to process any RCM command. Setting this
name to a value of 0 (zero) disables the timer. If this
name-value pair is not supplied, a default value is
assigned by the RCM.
Upon failure, the script must specify the failure rea‐
son using the name-value pair rcm_failure_reason and
exit with status 1.
register
The register command is invoked to allow a script to specify the
resources that it or its application handles that could potentially be
removed by DR. The script has to supply all its resource names to RCM
using the name-value pair rcm_resource_name.
Return Data:
If successful, the script must write the following
name-value pairs to stdout and exit with status 0:
rcm_resource_name=resourcename
rcm_resource_name=resourcename
.
.
.
where resourcename is the name of the resource the
script is interested in.
Upon failure, the script must specify the failure rea‐
son using the name-value pair rcm_failure_reason and
exit with status 1.
resourceinfo resourcename
The resourceinfo command is invoked to get the usage information about
resourcename.
Return Data:
If successful, the script must write the following
name-value pair to stdout and exit with status 0:
rcm_resource_usage_info=resource_usage
where resource_usage is a localized human readable mes‐
sage describing the usage of the resource by the
script.
Upon failure, the script must specify the failure rea‐
son using the name-value pair rcm_failure_reason and
exit with status 1.
queryremove resourcename
Prior to removing the resource from the system, the queryremove command
is invoked to query the script to determine whether the script can
release the given resource successfully from the service or application
it represents. The script does not actually release the resource. The
script might indicate that it is not able to release the resource if
the resource is critical for its service or application.
Additional environment parameter:
RCM_ENV_FORCE
Can be one of:
FALSE
Normal request.
TRUE
Request is urgent. The script should check
whether the resource can be released success‐
fully by force, such as by using the force
option to unmount a file system.
Return Data:
If the command succeeds, the script must return no data
and exit with status 0.
If the script would not be able to release the
resource, it must specify the reason using the name-
value pair rcm_failure_reason and exit with status 3.
Upon any other failure, the script must specify the
failure reason using the name-value pair rcm_fail‐
ure_reason and exit with status 1.
preremove resourcename
The preremove command is invoked prior to an attempt to remove the
given resourcename. In response to this command the script can either
release the resource (including closing the device if the device is
currently opened) from the service or application it represents or
indicate that it can not release the resource if the resource is criti‐
cal for its service or application.
Additional environment parameter:
RCM_ENV_FORCE
Can be one of:
FALSE
Normal request.
TRUE
Request is urgent. The script should make
extra effort to release the resource, such as
by using the force option to unmount a file
system.
Return Data:
If the command succeeds, the script must return no data
and exit with status 0.
If the script cannot release the resource, it must
specify the reason using the name-value pair rcm_fail‐
ure_reason and exit with status 3.
Upon any other failure, the script must specify the
failure reason using the name-value pair rcm_fail‐
ure_reason and exit with status 1.
postremove resourcename
The postremove command is invoked after the given resourcename has been
removed.
Return Data:
If the command succeeds, the script must return no data
and exit with status 0.
Upon failure, the script must specify the failure rea‐
son using the name-value pair rcm_failure_reason and
exit with status 1.
undoremove resourcename
The undoremove command is invoked to undo what was done in the previous
preremove command for the given resourcename. The script can bring the
state of the resource to the same state it was in when the script
received the preremove command for that resource.
Return Data:
If the command succeeds, the script must return no data
and exit with status 0.
Upon failure, the script must specify the failure rea‐
son using the name-value pair rcm_failure_reason and
exit with status 1.
Logging
A script must log all error and debug messages by writing to stdout the
name-value pairs listed below. The logged messages go to syslogd(1M)
with the syslog facility of LOG_DAEMON. See syslog.conf(4).
rcm_log_err=message
Logs the message with the syslog level of
LOG_ERR.
rcm_log_warn=message
Logs the message with the syslog level of
LOG_WARNING.
rcm_log_info=message
Logs the message with the syslog level of
LOG_INFO.
rcm_log_debug=message
Logs the message with the syslog level of
LOG_DEBUG.
A script can use the environment variable RCM_ENV_DEBUG_LEVEL to con‐
trol the amount of information to log. RCM_ENV_DEBUG_LEVEL is a numeric
value ranging from 0 to 9, with 0 meaning log the least amount of
information and 9 meaning log the most.
Installing or Removing RCM Scripts
You must use the following format to name a script:
vendor,service
where vendor is the stock symbol (or any distinctive name) of the ven‐
dor providing the script and service is the name of service the script
represents.
You must be a superuser (root) to install or remove an RCM script.
Select one of the following directories where you want to place the
script:
/etc/rcm/scripts
Scripts for specific systems
/usr/platform/`uname -i`/lib/rcm/scripts
Scripts for specific hardware implementation
/usr/platform/`uname -m`/lib/rcm/scripts
Scripts for specific hardware class
/usr/lib/rcm/scripts
Scripts for any hardware
Installing a Script
To install a script, copy the script to the appropriate directory from
the list above, change the userid and the groupid of the script to the
desired values, and send SIGHUP to rcm_daemon. For example:
# cp SUNW,sample.pl /usr/lib/rcm/scripts
# chown user[:group] /usr/lib/rcm/scripts/SUNW,sample.pl
# pkill -HUP -x -u root rcm_daemon
Removing a script
Remove the script from the appropriate directory from the list above
and send SIGHUP to rcm_daemon. For example:
# rm /usr/lib/rcm/scripts/SUNW,sample.pl
# pkill -HUP -x -u root rcm_daemon
EXAMPLES
Example 1 Site Customization RCM Script
#! /usr/bin/perl -w
#
# A sample site customization RCM script for a tape backup application.
#
# This script registers all tape drives in the system with RCM.
# When the system attempts to remove a tape drive by DR the script
# does the following:
# - if the tape drive is not being used for backup, it allows the
# DR to continue.
# - if the tape drive is being used for backup, and when DR is not
# forced (RCM_ENV_FORCE=FALSE) it indicates that it cannot release
# the tape drive with appropriate error message. When forced
# (RCM_ENV_FORCE=TRUE) it kills the tape backup application in
# order to allow the DR to continue.
#
# This script does not implement the postremove and undoremove commands
# since there is nothing to cleanup after DR remove operation is
# completed or failed. If any cleanup is needed after the DR removal
# completed, postremove command needs to implemented. If any cleanup is
# needed in the event of DR removal failure, undoremove command needs
# to be implemented.
#
use strict;
my ($cmd, %dispatch);
$cmd = shift(@ARGV);
# dispatch table for RCM commands
%dispatch = (
"scriptinfo" => do_scriptinfo,
"register" => do_register,
"resourceinfo" => do_resourceinfo,
"queryremove" => do_preremove,
"preremove" => do_preremove
);
if (defined($dispatch{$cmd})) {
&{$dispatch{$cmd}};
} else {
exit (2);
}
sub do_scriptinfo
{
print "rcm_script_version=1\n";
print "rcm_script_func_info=Tape backup appl script for DR\n";
exit (0);
}
sub do_register
{
my ($dir, $f, $errmsg);
$dir = opendir(RMT, "/dev/rmt");
if (!$dir) {
$errmsg = "Unable to open /dev/rmt directory: $!";
print "rcm_failure_reason=$errmsg\n";
exit (1);
}
while ($f = readdir(RMT)) {
# ignore hidden files and multiple names for the same device
if (($f !~ /^./) && ($f =~ /^[0-9]+$/)) {
print "rcm_resource_name=/dev/rmt/$f\n";
}
}
closedir(RMT);
exit (0);
}
sub do_resourceinfo
{
my ($rsrc, $unit);
$rsrc = shift(@ARGV);
if ($rsrc =~ /^devrmt([0-9]+)$/) {
$unit = $1;
print "rcm_resource_usage_info=Backup Tape Unit Number $unit\n";
exit (0);
} else {
print "rcm_failure_reason=Unknown tape device!\n";
exit (1);
}
}
sub do_preremove
{
my ($rsrc);
$rsrc = shift(@ARGV);
# check if backup application is using this resource
# if (the backup application is not running on $rsrc) {
# allow the DR to continue
# exit (0);
#}
#
# If RCM_ENV_FORCE is FALSE deny the operation.
# If RCM_ENV_FORCE is TRUE kill the backup application in order
# to allow the DR operation to proceed
#
if ($ENV{RCM_ENV_FORCE} eq 'TRUE') {
if ($cmd eq 'preremove') {
# kill the tape backup application
}
exit (0);
} else {
#
# indicate that the tape drive can not be released
# since the device is being used for backup by the
# tape backup application
#
print "rcm_failure_reason=tape backup in progress pid=...\n";
exit (3);
}
}
EXIT STATUS
A script must exit with following exit status values:
0
Operation specified by the given RCM command has been executed
successfully by the script. For queryremove command it also means
that the script can successfully release the resource.
1
An error occurred while processing the RCM command. The script
should provide the error message to RCM using the name-value pair
rcm_failure_reason before exiting.
2
The script does not support the given RCM command. A script must
exit with this status if it cannot understand the given RCM com‐
mand.
3
Indicates that the script cannot release the resource for prere‐
move and queryremove commands. The script should provide a message
to RCM specifying the reason for not being able to release the
resource using the name-value pair rcm_failure_reason before exit‐
ing.
ERRORS
If a script cannot successfully process an RCM command, it must supply
to the RCM a message indicating the reason for failure by writing a
name-value pair, in the form shown below, to stdout and exiting with
the appropriate exit status.
rcm_failure_reason=failure_reason
where failure_reason is a localized human readable message describing
the reason for failure of the RCM command.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌────────────────────┬─────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├────────────────────┼─────────────────┤
│Interface Stability │ Evolving │
└────────────────────┴─────────────────┘
SEE ALSOgettext(1), cfgadm(1M), cfgadm_scsi(1M), cfgadm_pci(1M), syslog(3C),
signal.h(3HEAD), syslog.conf(4), attributes(5), environ(5)NOTES
RCM scripts are expected to properly handle all RCM commands that the
script implements and to log all errors. Only root has permission to
add or remove an RCM script. An ill-behaved RCM script can cause unex‐
pected DR failures.
RCM commands are invoked only for the resources whose subsystems par‐
ticipate within the RCM framework. Currently, not all susbsystems par‐
ticipate within the RCM framework.
Feb 18, 2003 RCMSCRIPT(4)
