Uid's too big

Mats Wichmann mats at dual.UUCP
Fri Apr 13 02:49:33 AEST 1984


Another cute story about large UID number happened to one of our
customers once. They were also using employee numbers, and since
they are a VERY large company, the numbers were four- and five-digit.
This didn't really break any programs as such, but the lastlogin
mechanism in Berkeley V7 has a file to keep track of the last time
each user logged in. Presumably to cut down search time or something,
this is done by reserving space for each possible UID. Disk space
on the file system /usr/adm was residing on was real tight, and they
kept running out of space. Finally, we managed to trace this down
to /usr/adm/lastlog, which mysteriously grew to huge size after
certain users had logged in. We would have the poor guy delete the
file and reboot, and everything would be fine; then he logged in as
himself, and BOOM, /usr was out of space again. The little
feature reserving space for each possible user id in the lastlog file
was of course not documented anywhere....but it seems, in general,
to be a good idea to use user id's in the hundreds, if at all possible.

	    Mats Wichmann
	    Dual Systems Corp.
	    ...{ucbvax,amd70,ihnp4,cbosgd,decwrl,fortune}!dual!mats

  It now became apparent (despite the lack of library paste)	 
  that something had happened to the vicar;	[ Edward Gorey ]



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