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

mmcrlv Command

Name

mmcrlv - Creates logical volumes for use in an HACMP environment.

Synopsis

mmcrlv [-f FanoutNumber] [-y] -F DescFile

Description

The mmcrlv command is used to create logical volumes for use in a GPFS cluster environment. As such it follows the convention of creating one local volume group and one local logical volume per physical volume.

Where possible mmcrlv creates and imports volume groups and logical volumes in parallel. For instance, when multiple physical disks are specified in the disk descriptor file, their LVM components are created and imported by the nodes of the GPFS cluster in parallel.

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

Results

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

For each valid descriptor in the descriptor file, local logical volumes and the local volume groups are created.
The logical volume names are assigned according to the convention:

gpfsnumberlv
where number is a unique number not used in any prior logical volume named with this convention.

The local volume group component of the logical volume is named according to the same convention:

gpfsnumbervg
the local volume group
The local volume groups are imported to all nodes in the GPFS cluster.
The DescFile is rewritten to contain the created logical volume names in place of the physical disk or vpath name 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 mmcrlv process is enumerated during command execution. For example at step 1, the mmcrlv 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 mmcrlv command. For example at step one, the recorded comment would be:

#MMCRLV_STEP=1

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

After correcting the failing condition and restarting the mmcrlv command with the same descriptor file, the command prompts you to restart at the last failing step. For example, if a prior invocation of mmcrlv 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:::DiskUsage:FailureGroup

DiskName

The device name of the disk you want to use to create a logical volume. Each disk will be used to create a single volume group and a single logical volume.

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 adapter, 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.

Exit status

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

Security

You must have root authority to run the mmcrlv command.

You may issue the mmcrlv command from any node in the GPFS cluster.

A properly configured /.rhosts 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 mmcrcluster or the mmchcluster command, you must insure:

Proper authorization is granted to all nodes in the GPFS cluster.
The nodes in the GPFS cluster can communicate without the use of a password.

Examples

To create a logical volume with the descriptor file lvdesc, containing the descriptor records:
```
 hdisk2:::dataOnly:4
 hdisk3:::dataAndMetadata:5
```
These descriptors translate as:

Disk Name
hdisk2
Disk Usage
dataOnly
Failure Group
4

and

Disk Name
hdisk3
Disk Usage
dataAndMetadata
Failure Group
5
enter:
```
mmcrlv -F lvdesc
```
The file lvdesc is rewritten as
```
 gpfs32lv:::dataOnly:4
 gpfs33lv:::dataAndMetadata:5
```
A local volume group and logical volume are created:

gpfs32vg local volume group
gpfs32lv logical volume

Similarly, the local volume group gpfs33vg and logical volume gpfs33lv are created.
To create a logical volume with the descriptor file lvdesc2, containing the descriptor record:
```
hdisk1::::3
```
which translates as

Disk Name
hdisk1
Disk Usage
defaults to dataAndMetadata, allowing both
Failure Group
3
enter:
```
mmcrlv -F lvdesc2
```
Should the command fail at step two, the appropriate system and mmcrlv error messages are displayed. After correcting the errors, reissue the mmcrlv command. A prompt to continue is displayed:
```
A prior invocation of this command has recorded a partial
completion in the file (/tmp/lvdesc2).
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 file with the information for the logical volume that was created.

This command may only be issued in an HACMP environment.

Location

/usr/lpp/mmfs/bin

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