Clustering Linux Servers with the Concurrent Deployment of HP Serviceguard Linux and Red Hat Global File System for RHEL5, October 2008

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Legacy package configuration
After creating a legacy package configuration the guidelines described below needs to be
followed.
LV designators are used to specify the LVM2 volumes in case of Red Hat GFS for RHEL5 (similar to
what is used for Red Hat GFS 6.1). LVM2 device names are of the format /dev/mapper/vgX-lvY
where vgX is the volume group and lvY is the logical volume. Set the variable FS_TYPE, to “GFS”
to indicate Red Hat GFS file system. Set the parameters, FS_NAME, FILE_DIRECTORY, and
FS_MOUNT_OPT which are used to check whether the files system is already mounted, and if
required, mounts them. The parameters, FS_UMOUNT_OPT and FS_FSCK_OPT are incompatible
with Red Hat GFS file system. These variables will not be used at the time of package startup or
shutdown. Also the variable FS_MOUNT_RETRY is assumed to be “0”.
Since the GFS file system is not un-mounted during package shutdown, the vgchange_cmd and
VG[] variables are ignored.
Data replication is not yet supported in a Serviceguard for Linux environment that is concurrently
deployed with Red Hat GFS, and hence the variable DATA_REP must be “none”. The parameters
RAIDTAB, RAIDSTART, RAIDSTOP and MD[], are incompatible with Red Hat GFS file system and
hence are ignored.
Recommended configurations
The recommended network configuration requires dedicated heartbeat LAN with a bonded pair of
NICs (using Linux Channel Bonding) for both Serviceguard and Red Hat GFS heartbeats. Red Hat
GFS does not support multiple heartbeat networks, but, the channel-bonding provides the
additional HA protection.
Figure 2 is an example of the network configuration for a four node dual cluster. It has one
bonded pair of network paths for both Serviceguard and Red Hat GFS heartbeats and another
network for communication external to the cluster (bonded NICs are shown for the external
connections). This is the minimum supported network configuration. Dual port NICs can be used
for bonding, but for availability, bonded pairs should not use the connections from a single dual
port NIC.
The focus of the recommendations has been to eliminate the possibility of both clusters going
down by increasing redundancy of FC links and heartbeat networks.
FC link failures in Red Hat GFS for RHEL5 can cause the GFS mount points on shared storage to
be unavailable even after the FC link is restored. It requires that the failed node be rebooted after
the FC link(s) are restored. It is recommended to configure Serviceguard for Linux disk monitoring
service on all packages of a dual-cluster to allow failover when all FC link(s) fail.