since 2003 I'm documenting everything in our inhouse wiki.
Servers
- hardware specs
- waranty information
- network information
- and of course installed software and configuration
Workflows
e.g. how-to add or delete a user and give him/her access to all relevant services
Important links
- link to all your web interfaces
- link to the monitoring URLs (nagios, munin, apc-monitoring...)
- link to the wiki (for the printed version!)
Emergency instructions
what to do if intranet server/internet/web server/etc are down
Important:
Choose a wiki engine with easy export to PDF!
Its not useful if you are in holiday, the server running your wiki is down and no one knows what to do because your documentation is offline
Have a look at twiki, docuwiki or mediawiki.
BTW:
there is a OpenOffice.org plugin to write directly to mediawiki - very convenient.
EDIT:
Its also nice to write down some infos to /home/adminuser/maintenance
. This is done quick and can be very helpfull, if several admins work on a server. eg:
2009-06-27 -thorsten-
running aptitude update && aptitude full-upgrade
everything seems ok
2009-06-25 -andreas-
cups-pdf wasn't reachable. restarted cups
2009-06-23 -thorsten-
deleted old log under /var/log/squid
etc.