Designing High-Availability for Xen Virtual Machines with HP Serviceguard for Linux
Serviceguard for Linux Configuration
Storage Configuration
When you install the OS (xen-dom0), the fibre channel drivers ‘qla1280.ko’ and
‘qla2xxx/qla2xxx.ko’ do not get loaded by default. A modprobe on the driver module name
results in ‘Invalid module format’.
The procedure for loading the SCSI QLogic drivers is as follows:
1. Edit ‘/etc/modprobe.conf’, remove any ‘qla*’ and ‘scsi_adapter*’ alias lines.
Then add
alias scsi_adapter qla1280
alias scsi_adapter1 qla2xxx
Rebuild the ‘initrd’ file using the ‘mkinitrd’ command
2. On RHEL5.1, 5.2 use the ‘mkinitrd’ command with the listed arguments, to create an
‘initrd’
mkinitrd -v /boot/initrd-(uname -r).img $(uname -r)
On SUSE10 SP1, SP2 use ‘mkinitrd’ command with no arguments to create an
‘initrd’ in the ‘/boot’ directory
mkinitrd
Network Configuration
On RHEL5.1, 5.2 Xen dom0, a pseudo-network device with the name of ‘virbr0’ (default IP
address: ‘192.168.122.1’) will appear in the ‘ifconfig’ list. This device is configured and
controlled by ‘libvirt’. The device does not serve any purpose other than to provide a private
VM subnet. This is not necessary if the guest virtual machines are configured to use bridge
networking.
If the device is left configured (in the default state), SG/LX automatic network probing may report a
possible network partition on the ‘192.168.122.0’ subnet, when it detects it as a potential
heartbeat network. Since ‘192.168.122.0’ is meant to be a private subnet within Xen dom0 and
not meant to be visible beyond the local dom0, we suggest deconfiguring the device.
To unconfigure the device; remove the entries in the file ‘default.xml’ located at:
/etc/libvirt/qemu/networks/autostart/default.xml
Leaving it configured does not affect the operation of Serviceguard for Linux in any other way other
than what is mentioned above. SG/LX does not do automatic network probing for heartbeat
networks and manually configured heartbeat networks will not have this issue.
The virbr0 device is only seen on RHEL5.1 and RHEL5.2 platform. SLES10 SP1 and SLES10 SP2 do
not bring up the device by default.
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