A scrubber is a mechanism that provides overflow protection
in the event of a system halt.
The background scrubber has been replaced by a more robust
and efficient mechanism for recovering overflow after a system halt.
clear-file command, coldstart command, create-file command, FID, init-ovf command, Maxfid, Overflow table, set-ovf-reserve command, set-runaway-limit command, user-coldstart macro, what command