Designing High Availability Solutions with HP Serviceguard and HP Integrity Virtual Machines

• No communications are required between the VM guest and VM host.

• No security issues arise because application management authority is confined to the VM guest.

• Monitoring mechanisms (for example, ps command to monitor process IDs) are readily available from the VM

guest operating system.

The shortcomings of guest-based application monitoring include:

• A custom application monitor must be developed, tested, and maintained.

• The VM host has no visibility of applications status running within the VM guest.

• There is no host management (for example, starting or halting) of applications other than halting and restarting

their corresponding VM guest.

Host-based monitoring—A program, or “agent”, is used by the VM host system to probe the status of an application

running within the VM guest. In this method, a service defined within the Serviceguard VM guest package can be

implemented to monitor an application within the VM guest by either communicating directly with the application or

its customized monitoring agent running in the VM guest using a specific external network interface (for example, a

TCP/IP connection on a specific network port, UDP, etc.). The customized monitoring agent running within the VM

guest (if implemented) can be designed to provide status information about the application to the monitor service

associated with the VM guest package that can be written into log files located on the VM host. The returned

application status information would allow Serviceguard to detect an application failure and initiate a halt and

failover of its corresponding VM guest package. One example of host-based monitor for a guest-based application

would be the periodic retrieval of a known webpage from a guest-based Web server to verify that it was functioning

correctly. As with the guest-based monitoring agent, the host-based agent can recover from a detected application

failure by either restarting the application a defined number of times within the VM or halt the VM to trigger a

Serviceguard failover of the VM to another VM host cluster member.

Using host-based monitoring provides:

• Centralized monitoring of applications on all VM guests from the VM host.

• Tracking of individual application failures can be captured using log files on the VM host (must be custom-written).

• Serviceguard protection of the monitor by configuring the monitor as a package service of the VM guest.

The disadvantages of host-based monitoring include:

• The design and implementation of the monitoring agents and communication links can be complex.

• The monitors developed are application-specific.

• Communications between a VM guest and its VM host requires security authentication and authorization access

controls.

Serviceguard guest application monitoring

Starting with the Serviceguard A.11.19 and Integrity VM B.04.10 releases, HP supports the monitoring and control of

applications within a VM guest configured as a Serviceguard package. This functionality is available for any

application running in an HP-UX, Linux, or Windows VM guest using the Java Runtime Environment and provides the

following benefits:

• Can check the status of applications within VM guests from the VM host under the control of Serviceguard

• Provides startup and failure detection capabilities (restart, VM guest failover) for monitored VM guest applications

using Serviceguard functionality

• Provides a supported application monitoring framework without having to rely on custom-written software

The installation and configuration of Serviceguard guest application monitoring is documented in the HP Serviceguard

Toolkit for Integrity Virtual Servers User Guide available at: