.TH mmchnsd 02/16/06
mmchnsd Command
.SH "Name"
.PP
\fBmmchnsd\fR - Changes Network Shared Disk (NSD) configuration
parameters.
.SH "Synopsis"
.PP
\fBmmchnsd\fR
{"\fIDiskDesc\fR[;\fIDiskDesc\fR...]"
| \fB-F\fR \fIDescFile\fR}
.SH "Description"
.PP
The \fBmmchnsd\fR command serves several purposes:
.RS +3
.HP 3
1. Change either or both the primary and backup NSD server nodes.
.HP 3
2. Define a backup server node for an NSD that currently does not have
one.
.HP 3
3. Delete a backup server node for an NSD.
.HP 3
4. Delete both the primary and backup NSD server nodes. The disk must
now be SAN-attached to all nodes in the cluster.
.HP 3
5. Assign a primary and, if specified, a backup NSD server node. Nodes
that are not SAN-attached to the disk, or nodes that experience a local device
driver failure, will now have access to the data over the network from these
servers.
.RE
.PP
You must follow these rules when changing NSDs:
.RS +3
.HP 3
\(bu You must identify the disks by the NSD names that were given to them by
the
\fBmmcrnsd\fR command.
.HP 3
\(bu You must explicitly specify values for both the primary and backup NSD
server nodes even if you are only changing one of them.
.HP 3
\(bu The file system that contains the NSD being changed must be unmounted
prior to issuing the \fBmmchnsd\fR command.
.HP 3
\(bu The NSD must be properly connected to the new nodes prior to issuing the
\fBmmchnsd\fR command.
.HP 3
\(bu This command cannot be used to change the \fIDiskUsage\fR or
\fIFailureGroup\fR for an NSD. You must issue the \fBmmchdisk\fR command to change these.
.HP 3
\(bu To move a disk from one storage pool to another, use the \fBmmdeldisk\fR and \fBmmadddisk\fR commands.
.HP 3
\(bu You cannot change the name of the NSD.
.RE
.SH "Parameters"
.PP
.RS +3
\fB\fIDiskDesc\fR
\fR
.RE
.RS +9
A descriptor for each NSD to be changed. Each descriptor is
separated by a semicolon (;). The entire list must be enclosed in
single or double quotation marks.
.RE
.PP
.RS +3
\fB\fIDescFile\fR
\fR
.RE
.RS +9
Specifies a file containing a list of disk descriptors, one per
line.
.PP
Each disk descriptor must be specified in the form:
.sp
.nf
DiskName:PrimaryServer:BackupServer
.fi
.sp
.PP
.RS +3
\fB\fIDiskName\fR
\fR
.RE
.RS +9
The NSD name that was given to the disk by the \fBmmcrnsd\fR command.
.RE
.PP
.RS +3
\fB\fIPrimaryServer\fR
\fR
.RE
.RS +9
The name of the primary NSD server node. 
.PP
If this field is omitted, the disk is assumed to be SAN-attached to all
nodes in the cluster.
.PP
To change only the primary NSD server, ensure that if a backup NSD server
exists that you specify it, or the backup NSD server will be deleted.
Any parameter that is not specified defaults to null.
.sp
.nf
DiskName:PrimaryServer:BackupServer
.fi
.sp
.PP
To remove the primary GPFS server, explicitly skip the parameter:
.sp
.nf
DiskName
.fi
.sp
.RE
.PP
.RS +3
\fB\fIBackupServer\fR
\fR
.RE
.RS +9
The name of the backup NSD server node. 
.PP
If the \fIPrimaryServer\fR has not been specified and this field is
omitted, the disk is assumed to be SAN-attached to all nodes in the
cluster.
.PP
To remove the backup NSD server, explicitly skip the parameter, but ensure
you have specified the \fIPrimaryServer\fR or it will be removed
also:
.sp
.nf
DiskName:PrimaryServer
.fi
.sp
.RE
.PP
For information on how to specify node names, see \fISpecifying nodes as input to GPFS commands\fR
in \fIGPFS: Administration and Programming Reference\fR.
.RE
.SH "Options"
.PP
NONE
.SH "Exit status"
.PP
.PP
.RS +3
\fB0
\fR
.RE
.RS +9
Successful completion.
.RE
.PP
.RS +3
\fBnonzero
\fR
.RE
.RS +9
A failure has occurred.
.RE
.SH "Security"
.PP
You must have root authority to run the \fBmmchnsd\fR command.
.PP
You may issue the \fBmmchnsd\fR command from any node in the GPFS
cluster.
.PP
When using the \fBrcp\fR and \fBrsh\fR commands for remote
communication, a properly configured \fB.rhosts\fR file must exist
in the root user's home directory on each node in the GPFS
cluster. If you have designated the use of a different remote
communication program on either the
\fBmmcrcluster\fR
or the
\fBmmchcluster\fR command, you must
ensure:
.RS +3
.HP 3
1. Proper authorization is granted to all nodes in the GPFS cluster.
.HP 3
2. The nodes in the GPFS cluster can communicate without the use of a
password, and without any extraneous messages.
.RE
.SH "Examples"
.PP
If the disk \fBgpfs1nsd\fR is currently defined with
\fBk145n05\fR as its primary server and \fBk145n07\fR as its backup
NSD server, and you want to change the primary NSD server to
\fBk145n09\fR, issue this command:
.sp
.nf
mmchnsd "gpfs1nsd:k145n09:k145n07:::"
.fi
.sp
.PP
To confirm the changes, issue this command:
.sp
.nf
mmlsnsd -d "gpfs1nsd"
.fi
.sp
.PP
The system displays information similar to:
.sp
.nf
 File system   Disk name    Primary node             Backup node
 ---------------------------------------------------------------
 fs1           gpfs1nsd     k145n09                  k145n07
\ 
.fi
.sp
.SH "See also"
.PP
mmchdisk Command
.PP
mmcrcluster Command
.PP
mmcrnsd Command
.PP
mmlsnsd Command
.SH "Location"
.PP
\fB/usr/lpp/mmfs/bin\fR
.PP