.TH mmchcluster 02/16/06
mmchcluster Command
.SH "Name"
.PP
\fBmmchcluster\fR - Changes GPFS cluster configuration data.
.SH "Synopsis"
.PP
\fBmmchcluster\fR {[\fB-p\fR \fIPrimaryServer\fR]
[\fB-s\fR \fISecondaryServer\fR]}
.PP
Or,
.PP
\fBmmchcluster\fR \fB-p\fR \fBLATEST\fR
.PP
Or,
.PP
\fBmmchcluster\fR {[\fB-r\fR \fIRemoteShellCommand\fR]
[\fB-R\fR \fIRemoteFileCopyCommand\fR]}
.PP
Or,
.PP
\fBmmchcluster\fR \fB-C\fR \fIClusterName\fR
.PP
Or,
.PP
\fBmmchcluster\fR \fB-N
{\fR\fINodeDesc\fR[,\fINodeDesc\fR...] |
\fINodeFile\fR\fB}\fR
.SH "Description"
.PP
The \fBmmchcluster\fR command serves several purposes: 
.RS +3
.HP 3
1. Change the primary or secondary GPFS cluster configuration server.
.HP 3
2. Synchronize the primary GPFS cluster configuration server.
.HP 3
3. Change the remote shell and remote file copy programs to be used by the
nodes in the cluster.
.HP 3
4. Change the cluster name.
.HP 3
5. Specify node interfaces to be used by the GPFS administration
commands.
.RE
.PP
To display current system information for the cluster, issue the \fBmmlscluster\fR command.
.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.
.PP
When issuing the \fBmmchcluster\fR command with the \fB-p\fR
or \fB-s\fR flags, the nodes specified for these parameters must be
available in order for the command to succeed. If any of the nodes
listed are not available when the command is issued, a message listing those
nodes is displayed. You must correct the problem on each node and
reissue the command.
.PP
\fBAttention:\fR The \fBmmchcluster\fR command, when issued with
either the \fB-p\fR or \fB-s\fR option, is designed to operate in an
environment where the current primary and secondary cluster configuration
servers are \fInot\fR available. As a result, the command can run
without obtaining its regular serialization locks. To assure smooth
transition to a new cluster configuration server, no other GPFS commands
(\fBmm\fR commands) should be running when the command is issued, nor
should any other command be issued until the \fBmmchcluster\fR command has
successfully completed.
.SH "Parameters"
.PP
.RS +3
\fB\fB-C\fR \fIClusterName\fR
\fR
.RE
.RS +9
Specifies a new name for the cluster. If the user-provided name
contains dots, it is assumed to be a fully qualified domain name.
Otherwise, to make the cluster name unique, the domain of the primary
configuration server will be appended to the user-provided name. 
.PP
Since each cluster is managed independently, there is no automatic
coordination and propagation of changes between clusters like there is between
the nodes within a cluster. This means that if you change the name of
the cluster, you should notify the administrators of all other GPFS clusters
that can mount your file systems so that they can update their own
environments. See the
\fBmmauth\fR, \fBmmremotecluster\fR, and \fBmmremotefs\fR commands.
.RE
.PP
.RS +3
\fB\fB-N {\fR\fINodeDesc\fR[,\fINodeDesc\fR...]
| \fINodeFile\fR\fB}\fR
\fR
.RE
.RS +9
Specifies a list or file of node descriptors specifying node names for use
by the GPFS administration commands.
.PP
Each node descriptor has the following format:
.sp
.nf
daemonNodeName::adminNodeName:
.fi
.sp
.PP
.RS +3
\fB\fIDaemonNodeName\fR
\fR
.RE
.RS +9
Specifies the name of the node to be used by GPFS daemon to daemon
communication. The daemon node name may be specified as a short or long
node name, an IP address, or a node number.
.RE
.PP
.RS +3
\fB\fIAdminNodeName\fR
\fR
.RE
.RS +9
Specifies the name of the node to be used by GPFS administration commands
when communicating between nodes. The admin node name must be specified
as an IP address or a short or long node name that is resolved by the
\fBhost\fR command to the desired IP address.
.RE
.RE
.PP
.RS +3
\fB-p \fIPrimaryServer\fR
\fR
.RE
.RS +9
Change the primary server node for the GPFS cluster data. This may
be specified as a short or long node name, an IP address, or a node
number. 
.PP
\fBLATEST\fR - Synchronize all of the nodes in the GPFS cluster
ensuring they are using the most recently specified primary GPFS cluster
configuration server. If an invocation of the \fBmmchcluster\fR
command fails, you are prompted to reissue the command and specify
\fBLATEST\fR on the \fB-p\fR option to synchronize all of the nodes in
the GPFS cluster. Synchronization provides for all nodes in the GPFS
cluster to use the most recently specified primary GPFS cluster configuration
server.
.RE
.PP
.RS +3
\fB-s \fISecondaryServer\fR
\fR
.RE
.RS +9
Change the secondary server node for the GPFS cluster data. To
remove the secondary GPFS server and continue operating without it, specify a
null string, \fB"\fR\fB"\fR, as the parameter. This may
be specified as a short or long nodename, an IP address, or a node
number.
.RE
.SH "Options"
.PP
.RS +3
\fB-R \fIRemoteFileCopy\fR
\fR
.RE
.RS +9
Specifies the fully-qualified path name for the remote file copy program
to be used by GPFS.
.PP
The remote copy command must adhere to the same syntax format as the
\fBrcp\fR command, but may implement an alternate authentication
mechanism.
.RE
.PP
.RS +3
\fB-r \fIRemoteShellCommand\fR
\fR
.RE
.RS +9
Specifies the fully-qualified path name for the remote shell program to be
used by GPFS.
.PP
The remote shell command must adhere to the same syntax format as the
\fBrsh\fR command, but may implement an alternate authentication
mechanism.
.RE
.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 \fBmmchcluster\fR
command.
.PP
You may issue the \fBmmchcluster\fR command from any node in the GPFS
cluster.
.PP
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
To change the primary GPFS server for the cluster, issue this
command:
.sp
.nf
mmchcluster -p k164n06
.fi
.sp
.PP
The system displays output similar to:
.sp
.nf
mmchcluster: Command successfully completed
.fi
.sp
.PP
To confirm the change, issue this command:
.sp
.nf
mmlscluster
.fi
.sp
.PP
The system displays information similar to:
.sp
.nf
GPFS cluster information
========================
  GPFS cluster name:       cluster1.kgn.ibm.com
  GPFS cluster id:         680681562214606028
  GPFS UID domain:         cluster1.kgn.ibm.com
  Remote shell command:      /usr/bin/rsh
  Remote file copy command:  /usr/bin/rcp
GPFS cluster configuration servers:
-----------------------------------
  Primary server:    k164n06.kgn.ibm.com
  Secondary server:  k164n05.kgn.ibm.com
Node  Daemon node name   IP address   Admin node name    Designation
--------------------------------------------------------------------
 1  k164n04.kgn.ibm.com  198.117.68.68   k164n04.kgn.ibm.com  quorum
 2  k164n05.kgn.ibm.com  198.117.68.71   k164n05.kgn.ibm.com  quorum
 3  k164n06.kgn.ibm.com  198.117.68.70   k164sn06.kgn.ibm.com
.fi
.sp
.SH "See also"
.PP
mmaddnode Command
.PP
mmcrcluster Command
.PP
mmdelnode Command
.PP
mmlscluster Command
.PP
mmremotecluster Command
.SH "Location"
.PP
\fB/usr/lpp/mmfs/bin\fR
.PP