Grass Valley iControl V.6.02 - Manual (Page 476)

Backup and Redundancy
Manual Takeovers
466
Manual Takeovers
Manual Takeovers have an n+1 redundancy scheme. That is, iControl doesn’t limit the number
of Main Application Servers. iControl limits the number of Application Servers acting in a
Backup capacity to one within a single Redundancy Group. If more than one Backup server is
required, they should be put into separate N+1 Redundancy Groups.
For example, consider two Main (online) Application Servers plus one Backup Application
Server. The Backup is in a standby state and doesn’t run any processes used in normal
operation. To address the GSM as a single point-of-failure problem or GSM load balancing, we
may want to run two GSMs. GSM duties are thus load-balanced between the two Mains. When
an operator initiates a Manual Takeover from one of the Mains to the Backup, that portion of
the GSM duties being handled by the taken-over Main is switched to the Backup along with all
other services of this Application Server and its identity.
A Backup Application Server replicates the configuration data and identities of the n
Application Servers. From the iControl—Redundancy configuration page, a list of replication
profiles can be specified. The default replication frequency is 24 hours. This means that in the
case of an Application Server failure, any changes performed to the Application Server profile
in the previous 24 hours could be lost.
Auto-failovers
Auto-failovers have an n+1 redundancy scheme. That is, iControl doesn’t limit the number of
Main Application Servers. However, iControl does limit the number of Application Servers
acting in a Backup capacity to only one. When two or more Application Servers are configured
as a Redundancy Group on the iControl—Redundancy configuration page, any one of several
conditions can trigger an Auto-failover of service from a Main Application Server to the Backup
Application Server. In such cases, the Backup assumes the full role and identity of the original
(including its IP address if the Take over the main IP address after failover check box is
selected), and becomes the new Main. This process does not require user intervention except
in the initial Redundancy Group configuration and when performing failover recovery tasks
such as Reverse Takeovers or Replace operations.
In a Redundancy Group topology configured for Auto-failover, there may be multiple Main
Application Servers but only one Backup in an n+1 redundancy scheme.
See also
For more information about:
• Manual Takeovers, see "Configuring and Managing Application Server Redundancy" ,
on page 477.
• Redundancy Groups, see page 465 .
IMPORTANT: If you configure your Redundancy Group NOT to take over the Main’s IP address
upon failover or takeover, make sure you keep the Backup Application Server’s
IP address configured in System tools | Edit service locations | Service and
alarm discovery on all Application Servers that belong to the Redundancy
Group.