[CentOS] Anyway to ensure SSH availability?

I was having problems with the same server locking up to the point I can't even get in via SSH. I've already used HTB/TC to reserve bandwidth for my SSH port but the problem now isn't an attack on the bandwidth. So I'm trying to figure out if there's a way to ensure that SSH is given cpu and i/o priority.

However, so far reading seems to imply that it's probably not going to help if the issue is i/o related and/or it would require escalating SSH to such levels (above paging/filesystem processes) that makes it a really bad idea.

Since I'm not the only person who face problems trying to remotely access a locked up server, surely somebody must had come up with a solution that didn't involve somebody/something hitting the power button?