System Administration Guide: Devices and File Systems

Tape Backup RCM Script Example

This example illustrates how to use an RCM script for tape backups.

What the Tape Backup RCM Script Does

The tape backup RCM script performs the following steps:

Sets up a dispatch table of RCM commands.
Calls the dispatch routine that corresponds to the specified RCM command and exits with status 2 for unimplemented RCM commands.

Sets up the scriptinfo section.

rcm_script_func_info=Tape backup appl script for DR

Registers all tape drives in the system by printing all tape drive device names to stdout.
rcm_resource_name=/dev/rmt/$f
If an error occurs, the script prints the error information to stdout.
rcm_failure_reason=$errmsg

Sets up the resource information for the tape device.

rcm_resource_usage_info=Backup Tape Unit Number $unit

Sets up the preremove information by checking if the backup application is using the device. If the backup application is not using the device, the dynamic reconfiguration operation continues. If the backup application is using the device, the script checks RCM_ENV_FORCE. If RCM_ENV_FORCE is set to FALSE, the script denies the dynamic reconfiguration operation and prints the following message:
rcm_failure_reason=tape backup in progress pid=...
If RCM_ENV_FORCE is set to TRUE, the backup application is stopped, and the reconfiguration operation proceeds.

Outcomes of the Tape Backup Reconfiguration Scenarios

Here are the various outcomes if you use the cfgadm command to remove a tape device without the RCM script.

If you use the cfgadm command and the backup application is not using the tape device, the operation succeeds.
If you use the cfgadm command and the backup application is using the tape device, the operation fails.

Here are the various outcomes if you use the cfgadm command to remove a tape device with the RCM script.

If you use the cfgadm command and the backup application is not using the tape device, the operation succeeds.
If you use the cfgadm command without the -f option and the backup application is using the tape device, the operation fails with an error message similar to the following:
tape backup in progress pid=...
If you use the cfgadm -f command and the backup application is using the tape device, the script stops the backup application and the cfgadm operation succeeds.

Example—Tape Backup RCM Script

#! /usr/bin/perl -w
   #
   # A sample site customization RCM script.
   #
   # When RCM_ENV_FORCE is FALSE this script indicates to RCM that it cannot
   # release the tape drive when the tape drive is being used for backup.
   #
   # When RCM_ENV_FORCE is TRUE this script allows DR removing a tape drive
   # when the tape drive is being used for backup by killing the tape
   # backup application.
   #
    
    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 =~ /^\/dev\/rmt\/([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);
            }
    }