The listserv maintainer can be alerted when disks start getting full. This is controlled by the LOCAL SYSVARS file, normally stored on LISTSERV's A disk. There are MDISK statements that determine the % to start the warnings. Most of mine are set to 95%, so I start getting messages when a disk is 95% full. There is also a CHECKMDISK statement that is required to actually trigger the checking each time LISTSERV starts up.