Technical data

ServerIron ADX Graphical User Interface Guide 23
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High Availability
5
HA overview
To configure the HA feature on the ADX device, the setup requires two ADX devices, where one
device must be active and the other device must be in the standby mode. The active device
accepts connections and manages servers, and the standby device monitors the active device. If
the active device fails to accept connections, the standby device takes over the active device
functions. The HA for Server Load Balancing (SLB) consists of the following modes:
• Hot standby—This mode requires a setup of two ADX devices, where one device is always active
and the other device is always in the standby mode. The chassis devices support the hot
standby mode.
• Symmetric—This mode requires a setup of two ADX devices, where both the devices can
receive SLB traffic and both are active for the same VIP (virtual server).
NOTE
You can enable only one of the HA modes on the device.
For more information on high availability, refer to the ServerIron ADX Server Load Balancing Guide.
Configuring the ADX in hot standby mode
Hot standby allows you to configure two ADX devices to serve as a redundant pair. One device is
always active while the other device is always standby. If the active device fails, the idle standby
device assumes the active functions and becomes the new active device.
Hot standby is the only HA service counting the number of available router and server ports for
failover behavior. The device with the highest number of active ports is declared as the active
device. A failover is triggered when a system reload or crash triggers, in addition to the port-count
loss.
NOTE
Hot standby is supported only in switch code.
To configure hot standby on the device that runs switch code, perform the following steps within the
Configure Tab.
1. Click System on the menu bar.
2. From the sidebar, select High Availability.