I had a remote server running Debian Sarge that experienced some HDD failure and I meant to reboot it hoping that fsck could repair the errors automatically. I eventually drove out there and replaced the faulty disks...

But I was wondering: What other ways are there to force a Linux system to reboot that do not require hard drive access?

What I had tried:

• shutdown -r now Did not work, as shutdown is a program that would have to be loaded from disk, the error shown in the terminal was bash: /sbin/shutdown: Input/output error
• init 6 same as above
• telinit q same as above
• kill -2 1 This did not print an error, but did not work either. (However, it is possible that the Sarge init did not implement SIGINT, the sarge manpages did not mention it. So it could work in a more recent version of Debian)
• This guide on PCFreak.net. However, this failed at sysctl, which was not in memory either.