User guide

Appendix C - Redundancy C-9
VMS Redundancy
• with Auto Activate de-selected, a server will be activated only by an
operator manually issuing an Activate command on one of the servers.
When choosing to use Auto Activate, each VMS server in the redundant group
should be configured with the Auto Activate function selected.
Redundant Servers
The Redundant Servers box lists, by IP address, the other VMS servers that
are in the redundancy group with this server. Each VMS server in the group
must own a list that includes all of the other servers in that group.
Use the Add, Modify, and Remove buttons to create and maintain the list.
Priority
The Priority setting identifies where this server ranks in the redundant server
hierarchy for becoming active during a switch-over. The lower the number
entered, the higher the priority.
Set the Priority to a unique number in the range 0 to 31.
Caution: No two servers in a redundancy group should ever be assigned the
same priority; each server must have a unique number to prevent
contention.
Failover Time
The Redundancy Failover Time is set by specifying the values for Retry Delay
and Retry Count. The Failover Time is the amount of time that will pass prior
to a switch-over to a Standby server following a failure in communications with
the Active server.
The Retry Delay represents how long the system waits before sending another
heartbeat request. The Retry Count represents how many heartbeats are missed
before the device is determined to be offline. Failover Time is calculated by
taking twice the Retry Delay value and multiplying it by the Retry Count value.
Generally, it is recommended to use the following values:
• For networks with up to 100 nodes — Retry Delay = 500 ms,
Retry Count = 10.
• For networks with over 100 nodes — Retry Delay = 500 ms,
Retry Count = 20.
5. Configure the SNMP traps for this server. This may be required for relaying
server status information/alarms to a primary management system at the
NOC, for example.