VCS some notes.
GAB maintains cluster membership by receiving input on the status of the heartbeat from each node by LLT. when a system no longer receives heartbeats from peer, it marks the peer as Down and excludes the peer from the cluster. In VCS,
memberships are sets of system participating in the cluster. VCS has the following types of membership.
1. Regular membership : includes systems that communicate with each other across one or more network channels.
2. Jeopardy : Membership includes systems that have only one private communication link
3. DAEMON Down node Alive (DDNA) is a condition in which the VCS High availability daemon on a node fails,
but the node is running . in a DDNA condition, VCS does not have information about the state of service groups on the node.
so VCS places all service groups that were online on the affected node in the autodisabled state. Manual intervention is required to
to enable failover of autodisabled service groups. Admin must release the resources running on the affected
node, clear resource faults, and bring the service groups online on another node.
Cluster communications
GAB's second function is reliable cluster communications. GAB provides guaranteed delivery of point-to-point and
broadcast message to all nodes. VCS engine uses a private IOCTL ( Provided by GAB ) to tell GAB that it is alive.
LLT
VCS uses private network communications between cluster nodes for cluster maintenance. The Low Latency Transport functions aas a high performance low-latency replacement for the IP stack, and is used for all cluster communications. Symantec recommends two independent networks between all cluster nodes. these networks provide the required redundancy in the communications path and enable VCS TO DETERMINE a network failure and a system failure.
LLT has two major functions.
1. LLT distributes (load balances ) internode communications across all available private network links. This distribution means that all cluster communications are evenly distributed across all private network links (Maximum eight) for performance and fault resilence. If a link fails, traffic is redirected to the remaining links
2. Heartbeat
LLT is responsible for sending and receiving heartbeat traffic over network links. The Group Membership Services
function of GAB uses his heartbeat function to determine cluster membership.
GAB maintains cluster membership by receiving input on the status of the heartbeat from each node by LLT. when a system no longer receives heartbeats from peer, it marks the peer as Down and excludes the peer from the cluster. In VCS,
memberships are sets of system participating in the cluster. VCS has the following types of membership.
1. Regular membership : includes systems that communicate with each other across one or more network channels.
2. Jeopardy : Membership includes systems that have only one private communication link
3. DAEMON Down node Alive (DDNA) is a condition in which the VCS High availability daemon on a node fails,
but the node is running . in a DDNA condition, VCS does not have information about the state of service groups on the node.
so VCS places all service groups that were online on the affected node in the autodisabled state. Manual intervention is required to
to enable failover of autodisabled service groups. Admin must release the resources running on the affected
node, clear resource faults, and bring the service groups online on another node.
Cluster communications
GAB's second function is reliable cluster communications. GAB provides guaranteed delivery of point-to-point and
broadcast message to all nodes. VCS engine uses a private IOCTL ( Provided by GAB ) to tell GAB that it is alive.
LLT
VCS uses private network communications between cluster nodes for cluster maintenance. The Low Latency Transport functions aas a high performance low-latency replacement for the IP stack, and is used for all cluster communications. Symantec recommends two independent networks between all cluster nodes. these networks provide the required redundancy in the communications path and enable VCS TO DETERMINE a network failure and a system failure.
LLT has two major functions.
1. LLT distributes (load balances ) internode communications across all available private network links. This distribution means that all cluster communications are evenly distributed across all private network links (Maximum eight) for performance and fault resilence. If a link fails, traffic is redirected to the remaining links
2. Heartbeat
LLT is responsible for sending and receiving heartbeat traffic over network links. The Group Membership Services
function of GAB uses his heartbeat function to determine cluster membership.
