IBM PureData System for Analytics, Version 7.1

Differences with the previous Netezza HA solution

In previous releases, the IBM® Netezza® HA solution used the Red Hat Cluster Manager as the foundation for managing HA host systems. The Linux-HA solution uses different commands to manage the cluster. The following table outlines the common tasks and the commands that are used in each HA environment.

Table 1. HA tasks and commands (Old design and new design)
Task	Old command (Cluster Manager)	New command (Linux-HA)
Display cluster status	clustat -i 5	crm_mon -i5
Relocate NPS® service	cluadmin -- service relocate nps	/nzlocal/scripts/heartbeat_admin.sh --migrate
Enable the NPS service	cluadmin -- service enable nps	crm_resource -r nps -p target_role -v started
Disable the NPS service	cluadmin -- service disable nps	crm_resource -r nps -p target_role -v stopped
Start the cluster on each node	service cluster start	service heartbeat start
Stop the cluster on each node	service cluster stop	service heartbeat stop

Some additional points of differences between the solutions:

All Linux-HA and DRBD logging information is written to /var/log/messages on each host.
In the new cluster environment, pingd replaces netchecker (the Network Failure Daemon). pingd is a built-in part of the Linux-HA suite.
The cluster manager HA solution also required a storage array (the MSA500) as a quorum disk to hold the shared data. A storage array is not used in the new Linux-HA/DRBD solution, as DRBD automatically mirrors the data in the /nz and /export/home partitions from the primary host to the secondary host.
Note: The /nzdata and /shrres file systems on the MSA500 are deprecated.
In some customer environments that used the previous cluster manager solution, it was possible to have only the active host running while the secondary was powered off. If problems occurred on the active host, the Netezza administrator on-site would power off the active host and power on the standby. In the new Linux-HA DRBD solution, both HA hosts must be operational at all times. DRBD ensures that the data saved on both hosts is synchronized, and when Heartbeat detects problems on the active host, the software automatically fails over to the standby with no manual intervention.