.TH mmcrnsd 02/16/06
mmcrnsd Command
.SH "Name"
.PP
\fBmmcrnsd\fR - Creates cluster-wide names for Network Shared Disks
(NSDs) used by GPFS.
.SH "Synopsis"
.PP
\fBmmcrnsd\fR \fB-F\fR \fIDescFile\fR [\fB-v\fR {\fB\fIyes\fR\fR |\fBno\fR}]
.SH "Description"
.PP
The \fBmmcrnsd\fR command is used to create cluster-wide names for NSDs
used by GPFS.
.PP
This is the first GPFS step in preparing a disk for use by a GPFS
file system. A disk descriptor file supplied to this command is
rewritten with the new NSD names and that rewritten disk descriptor file can
then be supplied as input to the
\fBmmcrfs\fR, \fBmmadddisk\fR or \fBmmrpldisk\fR commands.
.PP
The name created by the \fBmmcrnsd\fR command is necessary since disks
connected at multiple nodes may have differing disk device names in
\fB/dev\fR on each node. The name uniquely identifies the
disk. This command must be run for all disks that are to be used in
GPFS file systems. The \fBmmcrnsd\fR command is also used to assign
a primary and backup NSD server that can be used for I/O operations on behalf
of nodes that do not have direct access to the disk.
.PP
To identify that the disk has been processed by the \fBmmcrnsd\fR command,
a unique NSD volume ID is written on sector 2 of the disk. All of the
NSD commands (\fBmmcrnsd\fR,
\fBmmlsnsd\fR, and \fBmmdelnsd\fR) use this unique NSD volume ID to
identify and process NSDs.
.PP
After the NSDs are created, the GPFS cluster data is updated and they are
available for use by GPFS.
.PP
When using an IBM  pSeries High Performance Switch
(pSeries HPS) in your configuration, it is suggested you process your disks in
two steps:
.RS +3
.HP 3
1. 
Create virtual shared disks on each physical disk through the \fBmmcrvsd\fR command.
.HP 3
2. 
Using the rewritten disk descriptors from the \fBmmcrvsd\fR command, create NSDs through the
\fBmmcrnsd\fR command.
.RE
.PP
\fBResults\fR
.PP
Upon successful completion of the \fBmmcrnsd\fR command, these tasks are
completed:
.RS +3
.HP 3
\(bu NSDs are created.
.HP 3
\(bu The \fIDescFile\fR contains NSD names to be used as input to the \fBmmcrfs\fR,
\fBmmadddisk\fR,
or the
\fBmmrpldisk\fR commands.
.HP 3
\(bu 
A unique NSD volume ID to identify the disk as an NSD has been written on
sector 2.
.HP 3
\(bu 
An entry for each new disk is created in the GPFS cluster data.
.RE
.SH "Parameters"
.PP
.RS +3
\fB-F \fIDescFile\fR
\fR
.RE
.RS +9
The file containing the list of disk descriptors, one per line.
Disk descriptors have this format:
.sp
.nf
DiskName:PrimaryServer:BackupServer:DiskUsage:FailureGroup:
DesiredName:StoragePool
.fi
.sp
.PP
.RS +3
\fB\fIDiskName\fR
\fR
.RE
.RS +9
.PP
The block device name appearing in \fB/dev\fR for the disk you want to
define as an NSD. Examples of disks accessible through a block device
are SAN-attached disks or virtual shared disks. If a
\fIPrimaryServer\fR node is specified, \fIDiskName\fR must be the
\fB/dev\fR name for the disk device on the primary NSD server node.
See the Frequently Asked Questions at publib.boulder.ibm.com/infocenter/clresctr/
topic/com.ibm.cluster.gpfs.doc/
gpfs_faqs/gpfsclustersfaq.html for the latest supported disk
types.
.PP
GPFS provides the
\fBmmcrvsd\fR helper
command. In an AIX environment, this command can be used to configure
virtual shared disks and make them accessible to nodes connected over a high
performance switch. The output disk descriptor file from an \fBmmcrvsd\fR command can be used as input to 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. If not all nodes in the cluster have access to
the disk, or if the file system to which the disk belongs is to be accessed by
other GPFS clusters, \fIPrimaryServer\fR must be specified.
.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 been specified and this field is omitted,
it is assumed you do not want failover in the event that the
\fIPrimaryServer\fR fails. If \fIBackupServer\fR is specified and
the \fIPrimaryServer\fR has not been specified, the command fails.
.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
.PP
.RS +3
\fB\fIDiskUsage\fR
\fR
.RE
.RS +9
Specify a disk usage or accept the default. This field is ignored
by the \fBmmcrnsd\fR command, and is passed unchanged to the output
descriptor file produced by the \fBmmcrnsd\fR command. Possible
values are: 
.PP
.RS +3
\fBdataAndMetadata
\fR
.RE
.RS +9
Indicates that the disk contains both data and metadata. This is
the default.
.RE
.PP
.RS +3
\fBdataOnly
\fR
.RE
.RS +9
Indicates that the disk contains data and does not contain
metadata.
.RE
.PP
.RS +3
\fBmetadataOnly
\fR
.RE
.RS +9
Indicates that the disk contains metadata and does not contain
data.
.RE
.PP
.RS +3
\fBdescOnly
\fR
.RE
.RS +9
Indicates that the disk contains no data and no file metadata. Such
a disk is used solely to keep a copy of the file system descriptor, and can be
used as a third failure group in certain disaster recovery
configurations. For more information, see
\fIGeneral Parallel File System: Advanced
Administration\fR and search on \fISynchronous mirroring utilizing
GPFS replication\fR.
.RE
.RE
.PP
.RS +3
\fB\fIFailureGroup\fR
\fR
.RE
.RS +9
A number identifying the failure group to which this disk belongs.
You can specify any value from -1 (where -1 indicates that the disk has no
point of failure in common with any other disk) to 4000. If you do not
specify a failure group, the value defaults to the NSD primary server node
number plus 4000. If an NSD server node is not specified, the value
defaults to -1. 
.PP
GPFS uses this information during data and metadata placement to assure
that no two replicas of the same block are written in such a way as to become
unavailable due to a single failure. All disks that are attached to the
same NSD server or adapter should be placed in the same failure group.
.RE
.PP
.RS +3
\fB\fIDesiredName\fR
\fR
.RE
.RS +9
Specify the name you desire for the NSD to be created. This name
must not already be used as another GPFS disk name, and it must not begin with
the reserved string 'gpfs'. 
.RS +3
\fBNote:\fR
.RE
.RS +9
This name can contain only the following characters: 'A'
through 'Z', 'a' through 'z', '0'
through '9', or '_' (the underscore). All other
characters are not valid.
.RE
.PP
If a desired name is not specified, the NSD is assigned a name according to
the convention:
.PP
.RS +3
\fBgpfs\fINN\fRnsd
\fR
.RE
.RS +9
where \fINN\fR is a unique nonnegative integer not used in any prior
NSD.
.RE
.RE
.PP
.RS +3
\fB\fIStoragePool\fR
\fR
.RE
.RS +9
Specifies the name of the storage pool that the NSD is assigned to.
This field is ignored by the \fBmmcrnsd\fR command, and is passed unchanged
to the output descriptor file produced by the \fBmmcrnsd\fR
command.
.RE
.RE
.PP
Upon successful completion of the \fBmmcrnsd\fR command, the
\fIDescFile\fR file is rewritten to contain the created NSD names in place
of the device name. Primary and backup NSD servers and
\fIdesiredName\fR are omitted from the rewritten disk descriptor and all
other fields, if specified, are copied without modification. The
original lines, as well as descriptor lines in error, are commented out and
preserved for reference. The rewritten disk descriptor file can then be
used as input to the
\fBmmcrfs\fR, \fBmmadddisk\fR, or the \fBmmrpldisk\fR commands. You must have
\fBwrite\fR access to the directory where the \fIDescFile\fR file is
located in order to rewrite the created NSD information.
.PP
The \fIDisk Usage\fR and \fIFailure Group\fR specifications in the
disk descriptor are preserved only if you use the rewritten file produced by
the \fBmmcrnsd\fR command. If you do not use this file, you must
either accept the default values or specify new values when creating disk
descriptors for other commands.
.SH "Options"
.PP
.RS +3
\fB -v {\fB\fIyes\fR\fR |\fBno\fR}
\fR
.RE
.RS +9
Verify the disk is not already formatted as an NSD.
.PP
A value of \fB-v yes\fR specifies that the NSD are to be created only
if the disk has not been formatted by a previous invocation of the
\fBmmcrnsd\fR command, as indicated by the NSD volume ID on sector 2 of the
disk. A value of \fB-v no\fR specifies that the disk is to be
formatted irrespective of its previous state. The default is \fB-v
yes\fR.
.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 \fBmmcrnsd\fR command.
.PP
You may issue the \fBmmcrnsd\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
To create your NSDs from the descriptor file \fBnsdesc\fR
containing: 
.sp
.nf
 sdav1:k145n05:k145n06:dataOnly:4::poolA\ 
 sdav2:k145n04::dataAndMetadata:5:ABC
.fi
.sp
.PP
Issue this command:
.sp
.nf
mmcrnsd -F nsdesc\ 
.fi
.sp
.PP
These descriptors translate as:
.PP
.RS +3
\fBDisk Name
\fR
.RE
.RS +9
sdav1
.RE
.PP
.RS +3
\fBPrimaryServer Name
\fR
.RE
.RS +9
k145n05
.RE
.PP
.RS +3
\fBBackupServer Name
\fR
.RE
.RS +9
k145n06
.RE
.PP
.RS +3
\fBDisk Usage
\fR
.RE
.RS +9
\fBdataOnly\fR
.RE
.PP
.RS +3
\fBFailure Group
\fR
.RE
.RS +9
4
.RE
.PP
.RS +3
\fBStorage Pool
\fR
.RE
.RS +9
poolA
.RE
.PP
and 
.PP
.RS +3
\fBDisk Name
\fR
.RE
.RS +9
sdav2
.RE
.PP
.RS +3
\fBServer Name
\fR
.RE
.RS +9
k145n04
.RE
.PP
.RS +3
\fBBackup Server Name
\fR
.RE
.RS +9
none
.RE
.PP
.RS +3
\fBDisk Usage
\fR
.RE
.RS +9
\fBdataAndMetadata,\fR allowing both
.RE
.PP
.RS +3
\fBFailure Group
\fR
.RE
.RS +9
5
.RE
.PP
.RS +3
\fBDesired Name
\fR
.RE
.RS +9
ABC
.RE
.PP
.RS +3
\fBStorage Pool
\fR
.RE
.RS +9
system
.RE
.PP
\fBnsdesc\fR is rewritten as 
.sp
.nf
#sdav1:k145n05:k145n06:dataOnly:4::poolA
gpfs20nsd:::dataOnly:4::poolA
#sdav2:k145n04::dataAndMetadata:5:ABC
ABC:::dataAndMetadata:5
.fi
.sp
.PP
The output is similar to this:
.sp
.nf
mmcrnsd: Processing disk sdav1
mmcrnsd: Processing disk sdav2
mmcrnsd: 6027-1371 Propagating the changes to all affected
                   nodes. This is an asynchronous process.
.fi
.sp
.SH "See also"
.PP
mmadddisk Command
.PP
mmcrfs Command
.PP
mmdeldisk Command
.PP
mmdelnsd Command
.PP
mmlsnsd Command
.PP
mmrpldisk Command
.SH "Location"
.PP
\fB/usr/lpp/mmfs/bin\fR
.PP