VERITAS Volume Manager 4.1 Hardware Notes

Hardware Notes

Dynamic LUN Expansion

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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.

Resizing a device that contains the only valid conﬁguration copy for a disk

group can result in dataloss if a system crash occurs during the resize.

Resizing a virtual disk device is a non-transactional operation outside the

control of VxVM. This means that the resize command may have to be

re-issued following a system crash. In addition, a system crash may leave the

private region on the device in an unusable state. If this occurs, the disk must

be reinitialized, reattached to the disk group, and its data resynchronized or

recovered from a backup.