Install guide

Tip

The time a node takes to reboot depends on several factors, including BIOS settings. Many

servers scan all of memory and then scan PCI buses for boot candidates from NICs or HBAs (of

which there should only be one). Disabling these scans and any other steps in the BIOS that take

time, will improve recovery performance. The grub.conf file often continues a built-in 5-second

delay for screen hold. Sometimes, every second counts.

4.1.1. Cluster Recovery Time

In RAC/GFS, the road to transaction resumption starts with GFS filesystem recovery, and this is nearly

instantaneous once fencing is complete. Oracle RAC must wait for CRS to recover the state of the

cluster, and then the RDBMS can start to recover the locks for the failed instance (LMS recovery). Once

complete, the redo logs from the failed instance must be processed. One of the surviving nodes must

acquire the redo logs of the failed node, and determine which objects need recovery. Oracle activity is

partially resumed as soon as RECO (DB recovery process) determines the list of embargoed objects

that need recovery. Once roll-forward is complete, all non-embargoed and recovered objects are

available. Oracle (and especially RAC) recovery is a complex subject, but its performance tuning can

result in reduced downtime. And that could mean $Ms in recovered revenue.

Tip

It is possible to push the CSS T imeout below 300 seconds, if the nodes can boot in 60 seconds

or less.

4.2. Network Topology

Clusterware requires a heartbeat network, and an inter-node network for moving database block

between nodes (GCS). T hese are usually the same network, and often the same network as the Red

Hat Cluster Suite network.

It is critical that Red Hat Cluster Suite operates heartbeat services over the private, bonded network and

not the public network. If the private network fails for a node, then this node must be removed from the

cluster. If the public network fails, the application tier cannot access the database on the node, but the

CRS VIP service is responsible for the public network.

Chapter 4. RAC/GFS Cluster Configuration