Remotely upgrading via yum

[Paul Nowosielski]

Dear all,

I have two remote boxes that are in need of upgrading.
One is running FC6 and the other FC8.

The FC6 box is running sshd, httpd, pptpd and acts as a firewall
box.

The FC8 box is just running mysqld.

I do not have physical access to these boxes.
If I am locked out it will be a major problem.

Does anyone have some advice they can lend me please?
I was wanting to upgrade with the yum upgrade command but I 
am wary. I have no experience with it and do not know what to expect.

Thank you,

Paul