HP-UX Logical Volume Manager and MirrorDisk/UX Release Notes (February 2007)

Logical Volume Manager and MirrorDisk/UX Release Notes
About this Document
This document provides information about the HP-UX 11i v3 release of Logical Volume Manager
(LVM) and MirrorDisk/UX.
LVM and MirrorDisk/UX Overview
LVM
Logical Volume Manager (product BaseLVM) is the HP-UX default Volume Manager. It provides
the user with flexibility in configuring and managing mass storage resources. In HP-UX 11i v3,
the LVM kernel and commands are bundled with the core HP-UX product.
MirrorDisk/UX
MirrorDisk/UX (product B2491BA) is an optionally purchased HP-UX product to enable LVM
mirroring functionality.
Overview of Changes
This release of LVM and MirrorDisk/UX is integrated with the new HP-UX 11i v3 mass storage
stack, and delivers significant performance, scalability, availability, and usability enhancements.
LVM has been enhanced to support larger logical volumes, temporary quiescing of volume
groups, and striping with mirroring. Operations that previously required deactivation or recreation
of a volume group—such as replacing a disk, resizing a LUN, and modifying volume group
characteristics—can now be performed online.
New and Changed Features in This Release
New Features
The following features are new with the HP-UX 11i v3 release of LVM:
• LVM Device Online Replacement (OLR): The pvchange command has a new option, -a,
that can be used to temporarily stop LVM accessing a device or device special file, and to
reenable access.
A white paper, described in “Related Documentation”, explains how OLR simplifies the
process of replacing or isolating disks.
• Volume Group Quiesce/Resume: Two new options, -Q and -R, have been added to the
vgchange command. These options temporarily quiesce an activated volume group and
resume it, respectively. Quiescing a volume group keeps its composite disk image in a
consistent state—without deactivating the volume group—so that disk management utilities
can snapshot all the disks in the volume group.
Using the -Q option, you can quiesce both read and write operations to the volume group,
or just write operations. While the volume group is quiesced, the vgdisplay command
reports the volume group access mode as "quiesced". The indicated I/O operations are
queued until the volume group is resumed, and commands that would modify the volume
group configuration return an error.
For more information on quiescing and resuming volume groups, see the vgchange(1M)
manpage or the Quiescing and Resuming a Volume Group section of the HP-UX System
Administrator's Guide: Logical Volume Management.
About this Document 5