Alternate Servers 
Alternate Servers
Definition
You can specify an alternate server when you define a spool server. This alternate server is used when the actual spool server is down or overloaded.
Use
When creating an SAP output device, enter a server that has a defined alternate server in the Spool server field. This ensures the requests for this output device will be processed.
Use of alternate server when spool server is unavailable
If you specified an alternate server when defining a spool server, the system will use this alternate server to process output requests when the actual spool server is unavailable.
Use of alternate server when spool server is overloaded
The load on a spool server is calculated using the number of spool work processes, the number of requests to be processed, and the number of pages. If a server is overloaded, processing of output requests may be delayed. If an alternate server is defined for this spool server, and load balancing is activated, the requests can be distributed among the servers.
If you activated load balancing for a server, there is no longer a guarantee that this server will process the requests in the order in which they were generated. Requests created later than others may be processed first, if they are processed by an alternate server that is not under high load.
