root partition full, what files / folders can I delete

[robert rottermann]

Hi there

I have a server running with an uptime of some 5 years..

root at susanne /var/log # uptime
  21:49:54 up 1939 days, 21:50,  1 user,  load average: 1.84, 2.04, 1.83

Its root partition has filled up to nearly 100%

root at susanne /var/log # df / -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/md2         20G   18G  1.1G  95% /

now my questions are:

1. what folders are in the root partition

2. What folder/files can I delete without killing anything?
     Like /tmp ...

3. how can I find out what folder in

thanks for your help

robert