Veritas cluster 4.0 can have upto 32 nodes.
LLT (Low-Latency Transport)
veritas uses a high-performance, low-latency protocol for cluster communications. LLT runs directly on top of the data link provider interface (DLPI) layer ver ethernet and has several major junctions:
Group membership services/Atomic Broadcast (GAB)
GAB provides the following:
High Availability Daemon (HAD)
The HAD tracks all changes within the cluster configuration and resource status by communicating with GAB. Think of HAD as the manager of the resource agents. A companion daemon called hashadow moniotrs HAD and if HAD fails hashadow attempts to restart it. Like wise if hashadow daemon dies HAD will restart it. HAD maintains the cluster state information. HAD uses the main.cf file to build the cluster information in memory and is also responsible for updating the configuration in memory.
So putting the above altogether we get:
There are three types of service groups:
When a service group appears to be suspended while being brought online you can flush the service group to enable corrective action. Flushing a service group stops VCS from attempting to bring resources online or take them offline and clears any internal wait states.
Resources are objects that related to hardware and software, VCS controls these resources through these actions:
When you link a parent resource to a child resource, the dependency becomes a component of the service group configuration. You can view the dependencies at the bottom of the main.cf file.
A proxy resource allows multiple service groups to monitor the same network interface. This reduces the network traffic that would result from having multiple NIC resources in different service groups monitoring the same interface.
The phantom resource is used to report the actual status of a service group that consists of only persistent resources. A service group shows an online status only when all of its nonpersistent resources are online. Therefore, if a service group has only persistent resources (network interface), VCS considers the group offline, even if the persistent resources are running properly. By adding a phantom resource, the status of the service group is hsown as online.
All node within the cluster must have a unique scsi-initiator-id, to set the scsi-initiator-id follow below:
OK> setenv scsi-initiator-id 6
|# prtconf -v # search through the listing finding scsi-initiator-id
Before you install VCS make sure you have the following perpared:
To install VCS follow below, remember that both hosts must be able to root rsh into each otherwithout requesting for a password: -