HP Serviceguard for Linux Version A.11.19 Release Notes, October 2009

New Online Package Configuration Capabilities
Serviceguard A.11.19 allows you to perform most configuration changes to modular
packages, and many changes to legacy packages, while the package is running. For
details, instructions, and caveats, see the section “Reconfiguring a Package” in chapter
7 of the latest version of Managing Serviceguard for Linux, and in particular the subsection
“Allowable Package States During Reconfiguration”.
For information about legacy and modular packages, see Chapter 6 of the latest version
of Managing Serviceguard for Linux.
New Preview Capabilities
Many variables affect package placement, including the availability of cluster nodes;
the availability of networks and other resources on those nodes; failover and failback
policies; and package weights, dependencies, and priorities, if you have configured
them. You can preview the effect on packages of certain actions or events before they
actually occur.
Serviceguard A.11.19 provides two ways to do this: you can use the preview mode
(-t) of Serviceguard commands, or you can use the cmeval (1m) command to simulate
different cluster states. Alternatively, you might want to model changes to the cluster
as a whole; cmeval allows you to do this.
For more information, see “Previewing the Effect of Cluster Changes” in Chapter 7 of
Managing Serviceguard for Linux.
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.
PR requires the sg_persist command, which you may need to install separately
from your distribution source (for example the Linux installation CD), depending on
your platform and Linux distribution.
22 Serviceguard for Linux Version A.11.19 Release Notes