Explanation:
When a Domino outage occurs, Fast Restart was intended to allow a new Domino instance to start while NSD diagnostics are being run on the initial instance. When diagnostics are completed the initial instance is automatically terminated.

Use of this feature requires approximately twice as much memory to run Domino. That is because during crash recovery there are two instances of the server in memory; the old instance under NSD and the new instance being launched. Some enterprise customers find that the under 30 second restart time more than justifies the cost of additional memory.

Additionally, the setting Debug_DisableOSFileLocks must equal 1 for Fast Restart to work properly.

Default:
When this setting is absent or set to 0 then Fast Restart is disabled.

Recommendation:
If you are able to require twice as much memory, and Domino is running under AIX 32 or Solaris 32, set SERVER_FAST_RESTART=1 and Debug_DisableOSFileLocks=1

For all other OS configurations, avoid misunderstandings by completely removing SERVER_FAST_RESTART and Debug_DisableOSFileLocks from the configuration.

Restrictions:
Introduced in Domino 8.0 for AIX 32 and Solaris 32. This feature does not yet work for any 64 bit version of AIX or Solaris.  This feature does not yet work for any version of Domino running under any OS other than AIX and Solaris.

Related Settings:
SERVER_FAST_RESTART_SCRIPT, Debug_DisableOSFileLocks

References:
Technote 1266170
Information on Domino Server Fast Restart
http://www.ibm.com/support/docview.wss?uid=swg21266170

Domino Configuration Tuner:
This setting is included in the DCT catalog of best practices.