The master host can store its configuration and state to a Berkeley DB spooling database. The spooling database can be installed on the master server or on a separate host. When the Berkeley DB spools into a local directory on the master host, the performance is better, but if you want to set up a shadow master host, you need to use a separate Berkeley DB spooling server (host). In this case, you have to choose a host with a configured RPC service. The master host connects through RPC to the Berkeley DB.
Using a shadow master host is more reliable, but using a separate Berkeley DB spooling host results in a potential security hole. RPC communication as used by the Berkeley DB can be easily compromised. Only use this alternative if your site is secure and if users can be trusted to access the Berkeley DB spooling host by means of TCP/IP communication.
If you choose to use Berkeley DB spooling without a shadow master, you don't need to set up a separate spooling server. Likewise, if you choose not to use Berkeley DB spooling, you can set up a shadow master host without setting up a separate spooling server.
Once you determine whether you need a separate spooling server, you will also need to determine the location for the spooling directory. The spooling directory must be local to the spooling server. A default value for the location of the spooling directory is recommended during installation but this default value is not suitable when the file server is different from the master host.
The requirements for the Berkeley DB spooling host are similar to the requirements for the master host:
The host must be a stable platform.
The host must not be excessively busy with other processing.
At least 60 – 120 Mbytes of unused main memory must be available to run the grid engine system daemons. For very large clusters that include many hundreds or thousands of hosts and tens of thousands of jobs in the system at any time, 1 GByte or more of unused main memory may be required and two CPUs may be beneficial.
(Optional) A separate spooling host must be installed before the master host.
(Optional) The directory, sge-root, should be installed locally, to cut down on network traffic.