The Novell SAN Management Interface (NSMI) is used by the BCC to communicate with and control the attached SAN device. This happens during a BCC failover when the LUNs must be promoted from Secondary to Primary in order to online the cluster resource. An example of LUN promotion is masking the LUN to make it visible to the cluster that is the failover target.
This section covers the following topics:
In order for a SAN manufacturer to be NSMI compliant, it must support a management interface that can be executed from one of the cluster nodes (for example, in a NetWare environment). Perl or Java interfaces or an NLM that implements a command line interface (CLI) for the SAN vendor are examples of compliant interfaces.
Generally, the only interfaces needed by the BCC are to mask or unmask LUNs and to break or create mirrors. One script is needed for each BCC resource on each SAN. As an example, an NSMI script could be written that performs the following tasks for a single BCC resource. This script would be executed by the NSMI when the BCC fails over the BCC resource from the primary cluster to the secondary cluster.
Unmask the LUN for the resource on the primary SAN so the nodes of the primary cluster can no longer access the LUN.
Break the mirror between the primary SAN and the secondary SAN for the given LUN.
Mask the LUN for the resource on the secondary SAN so the nodes of the secondary cluster can access the LUN.
Establish a mirror between the secondary SAN and the primary SAN for the given LUN.
However, the actual NSMI script you write depends upon the BCC functionality you actually require for your cluster environment. It is recommended that you consult the professional services organization of your SAN vendor for further details.
The NSMI is a scripting environment. You create a script for each BCC resource and the BCC uses the NSMI to execute that script during a BCC failover of that resource. Comments are added to the script by preceding them with the pound (#) sign. Furthermore, the NSMI supports script tokens that are replaced with actual values at runtime right before the script is executed.
IMPORTANT:Be careful when using these tokens because they may not always return the proper data. This can occur when NSS has never seen the LUN before (that is, on the secondary cluster). In this case, NSS has never seen the LUN and therefore does not know about the pools and volumes. This leads to missing data for some of the tokens. For example, the %pool% token would return an empty string.
This section contains the following topics:
The following table lists the valid tokens:
If the first line of the script contains #!, the rest of the line specifies the script interpreter. For example, "#!perl -w" uses Perl as the script interpreter and passes the "-w" switch directly to the perl interpreter. If the #! line is missing, the script is assumed to be a NetWare NCF file.
If the first or second line contains #@, then the rest of the line specifies parameters for the NSMI. The following table list valid NSMI parameters:
The following psuedo code example shows how to control a generic SAN. Note the following about the script:
This script will not compile and is meant only as an example. An appropriate script (not necessarily Perl) will need to be used to control the SAN. Consult your SAN vendor for further information.
The Perl script identification is designated in the first line (#!perl -w --noscreen).
The NSMI parameters -s1 -w120 -1 are passed in on the second line (#@ -s1 -w120 -1). These parameters tell the NSMI to delay for a maximum of 120 seconds, wait for the signal file to notify of completion, and to run the script synchronously.
The Perl END section is used to create the signal file which notifies the NSMI of script completion.
#!perl -w --noscreen
#@ -s1 -w120 -1
#
# This is a psuedo code Perl script example that shows how to use
# the NSMI scripting interface to control a SAN via the Novell
# Business Continuity Cluster (BCC). The functionality in this
# script will need to be replaced with the correct calls to control
# the SAN. Furthermore, errors are not properly handled in this
# script.
#
# THIS SCRIPT WILL NOT COMPILE AND IS MEANT ONLY AS AN EXAMPLE.
package Novell_Psuedo_Code_Script;
use lib ".";
use MySANVendorLibrary;
use strict;
use warnings;
use IO::Handle;
# Old Disk Configuration
my $OLD_SAN = 1; # SAN ID
my $OLD_WORKSET = 0; # Workset number
my $OLD_VBLOCK = 0; # VBlock number
my @OLD_WORKPORT = (38, 46); # Workport list
my $OLD_VDISK = 3; # iFolder1
my $OLD_LUN = 3; # The LUN number I wish to have
my $OLD_VLINK = 21; # The source link to the new SAN
my $OLD_TARGET_VDISK = 11; # The target vlink on this SAN
# New Disk Configuration
my $NEW_SAN = 2; # SAN ID
my $NEW_WORKSET = 0; # Workset number
my $NEW_VBLOCK = 0; # VBlock number
my @NEW_WORKPORT = (0, 2); # Workport list
my $NEW_VDISK = 3; # iFolder1
my $NEW_LUN = 3; # The LUN number I wish to have
my $NEW_VLINK = 21; # The source vlink to the old SAN
my $NEW_TARGET_VDISK = 11; # The target vlink on this SAN
####################################################################
# Unmask the old disk
print "Managing SAN $OLD_SAN\n";
Manage_San($OLD_SAN);
Manage_WorkSet($OLD_WORKSET);
Manage_VBlock($OLD_VBLOCK);
Reserve_San($OLD_SAN);
Manage_DiskGroup(0);
Break_Mirror($OLD_VLINK);
foreach my $workport (@OLD_WORKPORT)
{
Unmask_VDisk($workport, $OLD_VDISK);
}
Unreserve_San();
####################################################################
# Mask the new disk
print "Managing SAN $NEW_SAN\n";
Manage_San($NEW_SAN);
Manage_WorkSet($NEW_WORKSET);
Manage_VBlock($NEW_VBLOCK);
Reserve_San($NEW_SAN);
Manage_DiskGroup(0);
Break_Mirror($NEW_VDISK);
foreach my $workport (@NEW_WORKPORT)
{
Mask_VDisk($workport, $NEW_LUN, $NEW_VDISK);
}
Mirror_VDisk($NEW_VDISK, $NEW_VLINK);
Unreserve_San();
####################################################################
# Refresh the old data on the old SAN
####################################################################
Manage_San($OLD_SAN);
Manage_WorkSet($OLD_WORKSET);
Manage_VBlok($OLD_VBLOCK);
Reserve_San($OLD_SAN);
Manage_DiskGroup(0);
Mirror_VDisk($OLD_TARGET_VDISK, $OLD_VDISK);
Unreserve_San();
####################################################################
# Tell BCC the script is done
####################################################################
END
{
my $fh;
open $fh, ">", "%signalFile%";
}