mmcrvdisk command

Availability

Available on all IBM Storage Scale editions.

Description

The mmcrvdisk command creates one or more vdisks. Upon successful completion of the mmcrvdisk command, the vdisk stanza file is rewritten in a form that can be used as input to the mmcrnsd command.

Parameters

-F StanzaFile

Specifies a file that includes vdisk stanzas identifying the vdisks to be created.

Vdisk stanzas look like the following:

%vdisk: vdiskName=VdiskName
        rg=RecoveryGroupName
        da=DeclusteredArrayName
        blocksize=BlockSize
        size=Size
        raidCode=RAIDCode
        diskUsage=DiskUsage
        failureGroup=FailureGroup
        pool=StoragePool
        longTermEventLogSize=LongTermEventLogSize
        shortTermEventLogSize=ShortTermEventLogSize
        fastWriteLogPct=fastWriteLogPct

where:

vdiskName=VdiskName

Specifies the name you want to assign to the vdisk NSD that is 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.

Note: This name can contain the following characters only:

• Uppercase letters A through Z
• Lowercase letters a through z
• Numerals 0 through 9
• Underscore character (_)

All other characters are not valid.

rg=RecoveryGroupName

Specifies the recovery group where the vdisk is to be created.

da=DeclusteredArrayName

Specifies the declustered array within the recovery group where the vdisk is to be created.

blocksize=BlockSize

Specifies the size of the data blocks for the vdisk. This must match the block size planned for the file system. The valid values are:

For nWayReplicated RAID codes:

256 KiB, 512 KiB, 1 MiB, 2 MiB

For 4+2p and 4+3p RAID codes:

256 KiB, 512 KiB, 1 MiB, 2 MiB, 4 MiB, 8 MiB

For 8+2p and 8+3p RAID codes:

512 KiB, 1 MiB, 2 MiB, 4 MiB, 8 MiB, 16 MiB

For 16+2p and 16+3p RAID codes:

512 KiB, 1 MiB, 2 MiB, 4 MiB, 8 MiB, 16 MiB

Specify this value with the character K or M (for example, 512K).

If you are using the system pool as metadata only and placing your data in a separate pool, you can specify your metadata-only vdisks with one block size and your data vdisks with a different block size. Since a file system with different metadata and data block sizes requires the use of multiple GPFS storage pools, a file system placement policy is needed to direct user file data to the data storage pool.

size=Size

Specifies the size of the vdisk. If size=Size is omitted, it defaults to using all the available space in the declustered array. The requested vdisk size is equally allocated across all of the pdisks within the declustered array.

raidCode=RAIDCode

Specifies the RAID code to be used for the vdisk. Valid codes are the following:

Unreplicated

Indicates no replication. This should only be used for a log tip backup vdisk.

2WayReplication

Indicates two-way replication. This should only be used for a log tip vdisk.

3WayReplication

Indicates three-way replication.

4WayReplication

Indicates four-way replication.

4+2p

Indicates Reed-Solomon 4 + 2p.

4+3p

Indicates Reed-Solomon 4 + 3p.

8+2p

Indicates Reed-Solomon 8 + 2p.

8+3p

Indicates Reed-Solomon 8 + 3p.

16+2p

Indicates Reed-Solomon 16 + 2p.

16+3p

Indicates Reed-Solomon 16 + 3p.

diskUsage=DiskUsage

Specifies a disk usage or accepts the default. With the exception of the vdiskLog value, this field is ignored by the mmcrvdisk command and is passed unchanged to the output stanza file.

Possible values are the following:

dataAndMetadata

Indicates that the disk contains both data and metadata. This is the default for disks in the system pool.

dataOnly

Indicates that the disk contains data and does not contain metadata. This is the default for disks in storage pools other than the system pool.

metadataOnly

Indicates that the disk contains metadata and does not contain data.

descOnly

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 the section called "Synchronous mirroring utilizing GPFS replication" in the chapter on "Establishing disaster recovery for your GPFS cluster" of the IBM Storage Scale: : Administration Guide.

vdiskLog

Indicates that this is the log home vdisk for the recovery group.

The log home vdisk must be created before any vdisks that are exposed through NSD.

vdiskLogTip

Indicates that this is the log tip vdisk for the recovery group.

vdiskLogTipBackup

Indicates that this is the log tip backup vdisk for the recovery group.

vdiskLogReserved

Indicates a vdisk that should have the same size and RAID code as the log home vdisk but is otherwise unused.

This is used to equalize the space consumption in the declustered arrays that do not contain the log home vdisk.

failureGroup=FailureGroup

This field is ignored by the mmcrvdisk command and is passed unchanged to the output stanza file. It identifies the failure group to which the vdisk NSD belongs.

pool=StoragePool

This field is ignored by the mmcrvdisk command and is passed unchanged to the output stanza file. It specifies the name of the storage pool to which the vdisk NSD is assigned.

longTermEventLogSize=LongTermEventLogSize

Specifies the size of the long-term event log, rounding up to the block size if not aligned. The default value is 4MB.

longTermEventLogSize applies only to the log vdisk.

shortTermEventLogSize=ShortTermEventLogSize

Specifies the size of the short-term event log, rounding up to the block size if not aligned. The default value is 1MB.

shortTermEventLogSize applies only to the log vdisk.

fastWriteLogPct=FastWriteLogPct

Specifies the fraction of the remaining log space to be used for the fast-write log, after allocating space for the event logs. The default value is 90%.

fastWriteLogPct applies only to the log vdisk.

-v {yes | no }

Verification flag; a value of yes specifies that vdisk creation will only start if the buffer space requirements of other recovery groups can be verified. The default value is yes.

Exit status

0

Successful completion.

nonzero

A failure has occurred.

Security

You must have root authority to run the mmcrvdisk command.

The node on which the command is issued must be able to execute remote shell commands on any other node in the cluster without the use of a password and without producing any extraneous messages. For additional details, see the following IBM Storage Scale RAID: Administration topic: Requirements for administering IBM Storage Scale RAID.

See also

Location

/usr/lpp/mmfs/bin