Designing High-Availability for Xen Virtual Machines with HP Serviceguard for Linux

Secure Linux Settings
On RHEL5, for successful creation of virtual machines, and also for creation of volume groups, it is
required that appropriate role-based ‘selinux’ rules be placed on the files and directories related
to Xen and Serviceguard for Linux. On SLES10, ‘apparmor’ provides equivalent role-based
security for files and directories. For additional details on configuring ‘selinux’ or ‘apparmor’,
refer to RHEL5 [8] Deployment Guide or SLES10 Apparmor Administration Guide[9].
Domain Memory Ballooning
Memory allocation to dom0 and domU can be modified using the ‘max-mem’ and ‘mem-set’
parameters. These parameters are used in conjunction with the ‘xm’ commands.
When a domU is running, the ‘max-mem’ and ‘mem-set’ can be modified dynamically. Use the
‘xm mem-set’ command to increase the memory allocation for a dom0/domU
xm mem-set <dom-id> <mem>
The maximum memory allocation limit for a dom0 / domU can be set using the command
xm mem-max <dom-id> <mem>
For domU, expanding only works up to the amount initially allocated to a domain. However, it is
possible to modify these parameters before a guest VM is powered up through the DomU
configuration script.
maxmem = 500
memory = 500
Memory Ballooning is useful when Serviceguard for Linux is installed on machines with similar
architecture and mismatched hardware configuration. A Xen virtual machine package running with a
given amount of memory cannot be failed over to a machine where at least that same amount of
memory is not available. Using memory ballooning makes it possible to set the amount of memory
used by the guest VM at the time of package startup on the other machine. Without this, the package
may fail to start up on the recipient node.
Serviceguard for Linux on Xen host
This section describes installation and configuration tasks specific to Serviceguard for Linux running
on a Xen host. The configuration aims to provide high availability to virtual machines running on the
Xen host. The Serviceguard for Linux in-host model defines virtual machines as Serviceguard for Linux
packages.
RPM package dependency for installing Serviceguard for Linux 11.18 or
later
To install SG/LX successfully on a Xen Dom0, the ‘kernel-xen-devel’ rpm must be installed first.
This package is required to build the ‘deadman’
driver, which is compiled as part of SG/LX rpm
installation on Linux.
RHEL5.1, RHEL5.2, SLES10 SP1, and SLES10 SP2 provide the ‘kernel-xen-devel’ rpm with the
distribution.
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