.TH mmcrvsd 03/16/06
mmcrvsd Command
.SH "Name"
.PP
\fBmmcrvsd\fR - Creates virtual shared disks for use by GPFS.
.SH "Synopsis"
.PP
\fBmmcrvsd\fR [\fB-f\fR \fIFanoutNumber\fR]
[\fB-y\fR] [\fB-c\fR] \fB-F\fR \fIDescFile\fR
.SH "Description"
.PP
The \fBmmcrvsd\fR command can be used to create virtual shared
disks for subsequent use by the
\fBmmcrnsd\fR
command. IBM Virtual shared disk is a subsystem that permits
application programs that are running on different nodes of an RSCT peer
domain access a raw logical volume as if it were local at each of the
nodes. Virtual shared disks created with \fBmmcrvsd\fR follow the
convention of one local volume group, one local logical volume, one global
volume group, and one virtual shared disk per physical volume. After
the virtual shared disk is created, it is configured and started on each node
with a defined virtual shared disk adapter. See the
\fBupdatevsdnode\fR command in the correct manual for your environment
at: publib.boulder.ibm.com/clresctr/windows/public/rsctbooks.html.
.PP
The \fBmmcrvsd\fR command can be used only in the AIX
environment.
.PP
Where possible, the \fBmmcrvsd\fR command creates and starts virtual
shared disk components in parallel. For instance, when multiple
physical disk servers are specified in the disk descriptor file, their LVM
components are created in parallel. Starting of all virtual shared
disks, on all nodes, always occurs in parallel.
.PP
The \fBmmcrvsd\fR command may also be restarted should one of the steps
fail.
.PP
\fBResults\fR
.PP
Upon successful completion of the \fBmmcrvsd\fR command:
.RS +3
.HP 3
\(bu Virtual shared disks are created.
.sp
If a desired name \fBvsdname\fR is specified on the disk descriptor,
\fBmmcrvsd\fR uses that name for the name of the virtual shared
disk. If a desired name is not specified, the virtual shared disk is
assigned a name according to the convention:
.sp
.RS +3
\fBgpfs\fINN\fRvsd
\fR
.RE
.RS +9
where \fINN\fR is a unique nonnegative integer not used in any prior
virtual shared disk named with this convention.
.RE
.HP 3
\(bu Virtual shared disks are synchronously started on all nodes.
.HP 3
\(bu If a desired name \fBvsdname\fR is specified on the disk
descriptor, \fBmmcrvsd\fR uses that name as the basis for the names of the
global volume group, local logical volume, and local volume group according to
the convention:
.sp
.RS +3
\fBvsdnamegvg
\fR
.RE
.RS +9
the global volume group
.RE
.sp
.RS +3
\fBvsdnamelv
\fR
.RE
.RS +9
the local logical volume
.RE
.sp
.RS +3
\fBvsdnamevg
\fR
.RE
.RS +9
the local volume group
.RE
.HP 3
\(bu If a desired name is not specified, the global volume group, local logical
volume, and local volume group for the virtual shared disk are named according
to the convention:
.sp
.RS +3
\fBgpfs\fINN\fRgvg
\fR
.RE
.RS +9
the global volume group
.RE
.sp
.RS +3
\fBgpfs\fINN\fRlv
\fR
.RE
.RS +9
the local logical volume
.RE
.sp
.RS +3
\fBgpfs\fINN\fRvg
\fR
.RE
.RS +9
the local volume group
.RE
.sp
where gpfs\fINN\fRvsd was the name chosen for the virtual shared
disk.
.HP 3
\(bu The primary server is configured and the volume group is varied
online there.
.HP 3
\(bu The backup server is configured and the volume group is imported there,
but varied off.
.HP 3
\(bu The \fIDescFile\fR file is rewritten to contain the created virtual
shared disk names in place of any disk descriptors containing physical disk or
vpath names. Primary and backup servers are omitted from the rewritten
disk descriptor and all other fields, if specified, are copied without
modification. The rewritten disk descriptor file can then be used as
input to the
\fBmmcrnsd\fR command.
.RE
.PP
\fBError recovery\fR
.PP
Each step of the \fBmmcrvsd\fR process is enumerated during
command execution. For example at step 0, the \fBmmcrvsd\fR command
prints:
.sp
.nf
Step \fI0\fR: Setting up environment
.fi
.sp
.PP
As each step is started, its corresponding number is recorded in the
\fIDescFile\fR file as a comment at the end. This comment serves as
restart information to subsequent invocations of the \fBmmcrvsd\fR
command. For example at step one, the recorded comment would be:
.sp
.nf
#MMCRVSD_STEP=\fI0\fR
.fi
.sp
.PP
Upon failure, appropriate error messages from the failing system component
are displayed along with \fBmmcrvsd\fR error messages.
.PP
After correcting the failing condition and restarting the \fBmmcrvsd\fR
command with the same descriptor file, the command prompts you to restart at
the last failing step. For example, if a prior invocation of
\fBmmcrvsd\fR failed at step one, the prompt would be:
.sp
.nf
A prior invocation of this command has recorded a partial
completion in the file (/tmp/\fIDescFile\fR).
Should we restart at prior failing step(\fI1\fR)?[y]/n=>
.fi
.sp
.PP
The default response is \fBy\fR; yes restart at the prior failing
step.
.SH "Parameters"
.PP
.RS +3
\fB-F \fIDescFile\fR
\fR
.RE
.RS +9
The file containing the list of disk descriptors, one per line, in the
form:
.sp
.nf
DiskName:PrimaryServer:BackupServer:DiskUsage:FailureGroup:DesiredName:StoragePool
.fi
.sp
.PP
.RS +3
\fB\fIDiskName\fR
\fR
.RE
.RS +9
The device name of the disk you want to use to create a virtual shared
disk. This can be either an hdisk name or a vpath name for an SDD
device. GPFS performance and recovery processes function best with one
disk per virtual shared disk. If you want to create virtual shared
disks with more than one disk, refer to the correct manual for your
environment at: publib.boulder.ibm.com/clresctr/windows/public/rsctbooks.html
.RE
.PP
.RS +3
\fBPrimaryServer
\fR
.RE
.RS +9
The name of the virtual shared disk server node. This can be in any
recognizable form.
.RE
.PP
.RS +3
\fBBackupServer
\fR
.RE
.RS +9
The backup server name. This can be specified in any recognizable
form or allowed to default to none.
.RE
.PP
.RS +3
\fB\fIDisk Usage\fR
\fR
.RE
.RS +9
Specify a disk usage or accept the default (see
\fIGeneral Parallel File System: Concepts,
Planning, and Installation Guide\fR and search on \fIrecoverability
considerations\fR). This field is ignored by the \fBmmcrvsd\fR
command and is passed unchanged to the output descriptor file produced by the
\fBmmcrvsd\fR command. 
.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
.PP
.PP
\fBDisk usage considerations: \fR
.RS +3
.sp
.HP 3
1. The \fIDiskUsage\fR parameter is not utilized by the \fBmmcrvsd\fR
command but is copied intact to the output file that the command
produces. The output file may then be used as input to the
\fBmmcrnsd\fR command.
.sp
.HP 3
2. RAID devices are not well-suited for performing small block writes.
Since GPFS metadata writes are often smaller than a full block, you may find
using non-RAID devices for GPFS metadata better for performance.
.RE
.RE
.PP
.RS +3
\fB\fIFailure Group\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. All disks that
have a common point of failure, such as all disks that are attached to the
same virtual shared disk server node, should be placed in the same failure
group. The value is passed unchanged to the output descriptor file
produced by the \fBmmcrvsd\fR command. If you do not specify a
failure group, a failure group will be assigned later by the
\fBmmcrnsd\fR command.
.RE
.PP
.RS +3
\fB\fIDesiredName\fR
\fR
.RE
.RS +9
Specify the name you desire for the virtual shared disk to be
created. This name must not already be used as another GPFS or AIX 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. The maximum size of this name is 13
characters.
.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 \fBmmcrvsd\fR command, and is passed unchanged
to the output descriptor file produced by the \fBmmcrvsd\fR
command.
.RE
.RE
.SH "Options"
.PP
.RS +3
\fB-f \fIFanoutNumber\fR
\fR
.RE
.RS +9
The maximum number of concurrent nodes to communicate with during parallel
operations. The default value is 10.
.RE
.PP
.RS +3
\fB-y
\fR
.RE
.RS +9
Specifies no prompting for any queries the command may produce. All
default values are accepted.
.RE
.PP
.RS +3
\fB-c
\fR
.RE
.RS +9
Specifies to create Concurrent Virtual Shared Disks. This option is
valid only for disk descriptors that specify both a primary and a backup
virtual shared disk server.
.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 \fBmmcrvsd\fR command.
.PP
You may issue the \fBmmcrvsd\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 a virtual shared disk with the descriptor file \fBvsdesc\fR
containing: 
.sp
.nf
 hdisk2:k145n01:k145n02:dataOnly:4
 hdisk3:k145n06::dataAndMetadata:5:ABC
.fi
.sp
.PP
These descriptors translate as:
.PP
.RS +3
\fBDisk Name
\fR
.RE
.RS +9
hdisk2
.RE
.PP
.RS +3
\fBServer Name
\fR
.RE
.RS +9
k145n01
.RE
.PP
.RS +3
\fBBackup Server Name
\fR
.RE
.RS +9
k145n02
.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
\fBDesired Name
\fR
.RE
.RS +9
Name defaults to gpfs20vsd
.RE
.PP
and 
.PP
.RS +3
\fBDisk Name
\fR
.RE
.RS +9
hdisk3
.RE
.PP
.RS +3
\fBServer Name
\fR
.RE
.RS +9
k145n06
.RE
.PP
.RS +3
\fBBackup Server Name
\fR
.RE
.RS +9
none
.RE
.PP
.RS +3
\fBDisk Usage
\fR
.RE
.RS +9
\fBdataAndMetadata\fR
.RE
.PP
.RS +3
\fBFailure Group
\fR
.RE
.RS +9
5
.RE
.PP
.RS +3
\fBDesired Name
\fR
.RE
.RS +9
ABC
.RE
.PP
The low level components of the virtual shared disk \fBgpfs20vsd\fR are
created:
.PP
.RS +3
\fBgpfs20gvg
\fR
.RE
.RS +9
global volume group
.RE
.PP
.RS +3
\fBgpfs20lv
\fR
.RE
.RS +9
local logical volume
.RE
.PP
.RS +3
\fBgpfs20vg
\fR
.RE
.RS +9
local volume group
.RE
.PP
The low level components of the virtual shared disk \fBABC\fR are
created:
.PP
.RS +3
\fBABCgvg
\fR
.RE
.RS +9
global volume group
.RE
.PP
.RS +3
\fBABClv
\fR
.RE
.RS +9
local logical volume
.RE
.PP
.RS +3
\fBABCvg
\fR
.RE
.RS +9
local volume group
.RE
.SH "See also"
.PP
mmcrnsd Command
.SH "Location"
.PP
\fB/usr/lpp/mmfs/bin\fR
.PP