utmp corruption

[Russell J Fulton;ccc032u]

zsd at PIG.DREA.DND.CA (Jim Diamond) writes:

>Occasionally the "who" command complains loudly about what it
>finds in /etc/utmp.  In these cases the utmp file ends in text
>such as the following:

[..............]

There is a problem with utmp which I believe is inherent in SYSV and that
is that there is no locking mechanism on the file. Corruption such as this
occurs when two processes try to write to the file simultaneously. This
problem manifests its self in several other ways as well. 
1/ cuserid often returns the wrong name.
2/ accounting for connect time is often very inaccurate.
3/ accounting processes often fall over because of corrupt files.

The problems get worse the more users you get on the system. We have
a 240S which often has more than 50 users on it.

We have reported the problems to SGI and are trying to get them fixed.
Other vendors of SYS V systems *have* fixed this problem.

I have not been able to find out if it is still a problem in V.4.

Cheers, Russell.


-- 
Russell Fulton, Computer Center, University of Auckland, New Zealand.
<rj_fulton at aukuni.ac.nz>