Brocade Virtual ADX Server Load Balancing Guide (Supporting ADX v03.1.00) - Manual (Page 99)

Brocade Virtual ADX Server Load Balancing Guide 83
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Disabling or deleting VIPs and real ports
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Real server shutdown
The force shutdown feature (sometimes called the force delete feature) allows you to force
termination of existing SLB connections. This feature assumes that you already have shut down a
TCP/UDP service on the real server, or you have shut down the real server itself.
There are several methods for shutting down a service or server. Each method has consequences,
so choose the method that works best in your situation. The methods are as follows:
• Edit the real server configuration on the Brocade Virtual ADX to disable the TCP/UDP ports on
the server. For example, to disable port 80 (HTTP), you can use the port http disable command
at the real server level of the CLI. If you use this method, you do not need to re-define the real
server to add the server back to SLB. However, you do need to re-enable the disabled TCP/UDP
ports.
• Delete the real server from the Brocade Virtual ADX. This option immediately prevents new
connections. To safely delete the real server from the Brocade Virtual ADX, we recommend the
following procedure.
1. Under the real server, disable the application ports.
2. Check to ensure the current connections and session comes down to zero (in show server
real output).
3. Under VIP, unbind the real server.
4. Delete the real server.
The Brocade Virtual ADX allows existing connections to end normally or, if you have enabled
the force shutdown option, the Brocade Virtual ADX ends all connections within two minutes. If
you use this method and later want to re-add the real server to the Brocade Virtual ADX, you
must redefine the real server, then rebind the real server to the appropriate VIP.
• Shut down the real server itself, rather than change definitions on the Brocade Virtual ADX.
When the real server stops responding to health checks, the Brocade Virtual ADX removes the
server from the SLB. This option is simple because it does not require any configuration
changes on the Brocade Virtual ADX. However, this option immediately disconnects all users,
whereas the above options allow the server or service to gracefully shut down (unless you use
the force shutdown option).
Port holddown timer
When a real server port fails, a Brocade Virtual ADX stops sending any new connections to the port.
Configuring the server force-delete command ensures that existing sessions are terminated within
two minutes. If a real server port fails and recovers before the force-delete operation has
completed, stale sessions can potentially cause problems for clients seeking access to the real
servers.
Enabling the port holddown timer disallows a failed port from being marked active until all idle
sessions have timed out. Thus, when a real port fails and recovers before a configurable timeout
(default 2 minutes) has elapsed the port is not allowed to move to the active state and is held in a
special helddown state. This is a pseudo-state while the port transitions from active to failed and
then to testing. If the subsequent health check is successful, the port is marked as active.
If all the ports bound to a VIP are in the helddown state, the VIP would still be in the inactive state.
The behavior of VIP health does not change. Where VIP health is concerned, a real port in the
helddown state is equivalent to a real port in the failed state.