How do I limit I/O usage for a user/process? A user broke my system

[Magnus Ahriman]

Hi,

Today I had a user who decided to open a very large text file in pico. The
result was a complete denial of service of the system and everything
stalled/was working veeeeery slowly.
Even after the user had killed the process it took quite some while for the
system to recover and I seemed to notice improvements of certain services
after having restarted them.

What are my options to limit resource usage for users? I tried renicing the
user's process but to no help and the problem was most certainly with disk
I/O. I don't want a normal user being able to lock up my entire system just
by viewing text files. So any ideas?

Best regards,
Magnus