Veritas Volume Manager 5.0 Administrator's Guide (September 2006)

105Administering disks

Dynamic LUN expansion

Note: A Storage Foundation license is required to use the dynamic LUN expansion

feature.

The following form of the

vxdisk command can be used to make VxVM aware of the

new size of a virtual disk device that has been resized:

# vxdisk [-f] [-g diskgroup] resize {accessname|medianame} \

[length=value]

The device must have a SCSI interface that is presented by a smart switch, smart array or

RAID controller. Following a resize operation to increase the length that is defined for a

device, additional disk space on the device is available for allocation. You can optionally

specify the new size by using the

length attribute.

If a disk media name rather than a disk access name is specified, the disk group must

either be specified using the -g option or the default disk group will be used. If the default

disk group has not been set up, an error message will be generated.

This facility is provided to support dynamic LUN expansion by updating disk headers and

other VxVM structures to match a new LUN size. It does not resize the LUN itself.

Any volumes on the device should only be grown after the device itself has first been

grown. Otherwise, storage other than the device may be used to grow the volumes, or the

volume resize may fail if no free storage is available.

Resizing should only be performed on devices that preserve data. Consult the array

documentation to verify that data preservation is supported and has been qualified. The

operation also requires that only storage at the end of the LUN is affected. Data at the

beginning of the LUN must not be altered. No attempt is made to verify the validity of pre-

existing data on the LUN. The operation should be performed on the host where the disk

group is imported (or on the master node for a cluster-shared disk group).

Resizing of LUNs that are not part of a disk group is not supported.It is not possible to

resize LUNs that are in the boot disk group (aliased as bootdg), in a deported disk group,

or that are offline, uninitialized, being reinitialized, or in an error state.

Caution: Do not perform this operation when replacing a physical disk with a disk of a

different size as data is not preserved.

Before reducing the size of a device, any volumes on the device should first be reduced in

size or moved off the device. By default, the resize fails if any subdisks would be disabled

as a result of their being removed in whole or in part during a shrink operation.

If the device that is being resized has the only valid configuration copy for a disk group,

the -f option may be specified to forcibly resize the device.