Managing HP Serviceguard for Linux Ninth Edition, April 2009

for startup. If auto_run is set to no, then the package simply halts without starting up
anywhere else.
The process for configuring disk monitoring is described in “Creating a Disk Monitor
Configuration” (page 220).
More Information on LVM
Refer to the section “Creating the Logical Volume Infrastructure” in Chapter 5 for
details about configuring volume groups, logical volumes, and file systems for use in
Serviceguard packages.
Refer to the article, Logical Volume Manager HOWTO on the Linux Documentation
Project page at http://www.tldp.org for a basic description of Linux LVM.
About Persistent Reservations
As of A.11.19, Serviceguard for Linux packages use persistent reservations (PR)
wherever possible to control access to LUNs. Persistent Reservations, defined by the
SCSI Primary Commands version 3 (SPC-3) standard, provide a means to register I/O
initiators and specify who can access LUN devices (anyone, all registrants, only one
registrant) and how (read-only, write-only).
Unlike exclusive activation for volume groups, which does not prevent unauthorized
access to the underlying LUNs, PR controls access at the LUN level. Registration and
reservation information is stored on the device and enforced by its firmware; this
information persists across device resets and system reboots.
NOTE: Persistent Reservations coexist with, and are independent of, activation
protection of volume groups. You should continue to configure activation protection
as instructed under Enabling Volume Group Activation Protection. Subject to the Rules
and Limitations spelled out below, Persistent Reservations will be applied to the cluster's
LUNs, whether or not the LUNs are configured into volume groups.
Advantages of PR are:
• Consistent behavior.
Whereas different volume managers may implement exclusive activation differently
(or not at all) PR is implemented at the device level and does not depend on
volume-manager support for exclusive activation.
• Packages can control access to LUN devices independently of a volume manager.
Serviceguard's support for the OCFS2 file system and ASM manager allows packages
whose applications use these protocols to access storage devices directly, without
using a volume manager.
About Persistent Reservations 85