Domino Fast Server Restart was introduced in Domino 8, it was designed for 32 bit versions of AIX and Solaris. The idea was in the event of a server crash the server could be restarted, while NSD was still running to collect diagnostics on the crashed server. The only caveat was that you were required to have sufficient memory to run both the crashed instance, and the new instance. The good news is Server Fast Restart is disabled by default, I don’t know how many people implemented it (I remember testing it at one point, but don’t believe I ever enabled it on a production server). Server Fast Restart is not supported in 64 bit versions of Domino, and IBM is now recommending that Fast Restart not be used at all. Other technotes related to Fast Server Restart seemed to have vanished. Might be worth double checking the old notes.ini file and make sure you have it disabled.
Disabling FAST RESTART Remove the following .ini parameters: SERVER_FAST_RESTART=1 DEBUG_DISABLEOSFILELOCKS=1 SERVER_FAST_RESTART_INSTANCE=n
Technote 1450877 It is not recommended to use Domino FAST RESTART on any platform with any version of Domino Notes and Domino Wiki: SERVER_FAST_RESTART