IBM General Parallel File System for AIX: Administration and Programming Reference

mmcrvsd Command

Name

mmcrvsd - Creates virtual shared disks for use by GPFS in an SP environment.

Synopsis

mmcrvsd [-f FanoutNumber] [-y] [-c] -F DescFile

Description

The mmcrvsd command is used to create virtual shared disks for use by GPFS. As such it follows the convention of creating 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 SP node with a defined virtual shared disk adapter (see the updatevsdnode command in IBM Parallel System Support Programs for AIX: Managing Shared Disks).

Where possible mmcrvsd 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.

The mmcrvsd command is also restartable should a creation step fail. See Error Recovery.

Results

Upon successful completion of the mmcrvsd command, these tasks are completed on all GPFS nodes in the nodeset:

Virtual shared disks are created.
The names are assigned according to the convention:

gpfsnumbervsd
where number is a unique number not used in any prior virtual shared disk named with this convention.
Virtual shared disks are synchronously started on all nodes.
Appropriate global volume groups, logical volumes, and local volume groups are created.
The global volume group, local logical volume, and local volume group components of the virtual shared disk are named according to the same convention:

gpfsnumbergvg
the global volume group
gpfsnumberlv
the local logical volume
gpfsnumbervg
the local volume group
The primary server is configured and the volume group is varied on there.
The backup server is configured and the volume group is imported there, but varied off.
The DescFile 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 mmcrfs, mmadddisk, mmchdisk, or the mmrpldisk commands.

Error Recovery

Each step of the mmcrvsd process is enumerated during command execution. For example at step 1, the mmcrvsd command prints:

Step 1: Setting up environment

As each step is started, its corresponding number is recorded in the DescFile file as a comment at the end. This comment serves as restart information to subsequent invocations of the mmcrvsd command. For example at step one, the recorded comment would be:

#MMCRVSD_STEP=1

Upon failure, appropriate error messages from the failing system component are displayed along with mmcrvsd error messages.

After correcting the failing condition and restarting the mmcrvsd command with the same descriptor file, the command prompts you to restart at the last failing step. For example, if a prior invocation of mmcrvsd failed at step one, the prompt would be:

A prior invocation of this command has recorded a partial
completion in the file (/tmp/DescFile).
Should we restart at prior failing step(1)?[y]/n=>

The default response is y; yes restart at the prior failing step.

Parameters

-F DescFile

The file containing the list of disk descriptors, one per line, in the form:

DiskName:PrimaryServer:BackupServer:DiskUsage:FailureGroup

DiskName

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 IBM Parallel System Support Programs for AIX: Managing Shared Disks manual.

PrimaryServer

The name of the virtual shared disk server node. This can be in any recognizable form.

BackupServer

The backup server name. This can be specified in any recognizable form or allowed to default.

Disk Usage

Specify a disk usage or accept the default (see the IBM General Parallel File System for AIX: Concepts, Planning, and Installation Guide and search for recoverability considerations):

dataAndMetadata (default)
dataOnly
metadataOnly

Failure Group

Specify a failure group or allow to default (see the IBM General Parallel File System for AIX: Concepts, Planning, and Installation Guide and search for recoverability considerations). 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.

Options

-f FanoutNumber: The maximum number of concurrent nodes to communicate with during parallel operations. The default value is 10.
-y: Specifies no prompting for any queries the command may produce. All default values are accepted.
-c: Specifies to create Concurrent Virtual Shared Disks. This option is only valid for disk descriptors that specify both a primary and a backup virtual shared disk server.

Exit status

0: Successful completion.
1: A failure has occurred.

Security

You must have root authority to run the mmcrvsd command.

Verify the authentication method set for SP security services:

If your authentication method is set to compatibility, Kerberos authentication is required. Issue the k4init command.
If your authentication method is set to DCE, dce_login authentication is required.
If your authentication method is set to NONE/std, there must be an entry in the /etc/sysctl.mmcmd.acl file on every node in the nodeset for the root user at every other node in the nodeset.

For further information, see the latest IBM Parallel System Support Programs for AIX: Administration Guide, IBM Parallel System Support Programs for AIX: Command and Technical Reference, and RS/6000: Planning Volume 2, Control Workstation and Software Environment manuals at www.rs6000.ibm.com/resource/aix_resource/sp_books/pssp. Search for information on sysctl.

You may issue the mmcrvsd command from any node running GPFS nodeset or the CWS.

If you are executing the mmcrvsd command from the CWS on a multi-partitioned system, the SP_NAME environment variable must be properly set. It is suggested that you use a separate window for each partition and set the environment variable accordingly. For further information, see the IBM Parallel System Support Programs for AIX: Administration Guide and search for understanding system partitioning.

Examples

To create a virtual shared disk with the descriptor file vsdesc containing:
```
 hdisk2:sp1sw05:sp1sw06:dataOnly:4
 hdisk3:sp1sw10::dataAndMetadata:5
```
These descriptors translate as:

Disk Name
hdisk2
Server Name
sp1sw05
Backup Server Name
sp1sw06
Disk Usage
dataOnly
Failure Group
4

and

Disk Name
hdisk3
Server Name
sp1sw10
Backup Server Name
none
Disk Usage
dataAndMetadata
Failure Group
5
enter:
```
mmcrvsd -F vsdesc
```
vsdesc is rewritten as
```
 gpfs20vsd:::dataOnly:4
 gpfs21vsd:::dataAndMetadata:5
```
The low level components of the virtual shared disk gpfs20vsd are created:

gpfs20gvg global volume group
gpfs20lv local logical volume
gpfs20vg local volume group

Similarly, the low level components of the virtual shared disk gpfs21vsd are created.
To create a virtual shared disk with a descriptor file vsdesc2 containing:
```
vpath1:sp1sw07:sp1sw08::3
```
which translates as

Disk Name
vpath1
Server Name
sp1sw07
Backup Server Name
sp1sw08
Disk Usage
defaults to dataAndMetadata, allowing both
Failure Group
3
enter:
```
mmcrvsd -F vsdesc2
```
Should the command fail at step two, the appropriate system and mmcrvsd error messages are displayed. After correcting the errors, reissue the mmcrvsd command. The following is displayed:
```
A prior invocation of this command has recorded a partial
completion in the file (/tmp/vsdesc2).
Should we restart at prior failing step(2)?[y]/n=>
```
A reply of y allows the command to continue processing at the point of failure and run to completion or subsequent failure.

See also

Restrictions

You must have write access to the directory where the DescFile file is located in order to record all completed steps and rewrite the created virtual shared disk information.

This command may only be issued in an SP environment.

Location

/usr/lpp/mmfs/bin

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gpfs20gvg	global volume group
gpfs20lv	local logical volume
gpfs20vg	local volume group