Hello,

I am a novice Linux server administrator so please bear with me.

One of the server I manage is a web server which runs normally most of the day, but in the morning as it's backing up the mysql database, the load avg goes sky high and the server eventually comes to a halt, requiring me to hardboot it.

How can I go about fault finding here?

The server is:

1.8 GHz 2MB Cache Intel® Core™ 2 Duo processor
512 MB RAM and 80 GB hard disk drive

Let me know if you would like me to post my.cnf or httpd.conf's settings

Many thanks!

Does this machine have to run 24/7 ?

If it crashes under heavy load it could be bad RAM (-> memtest), bad ventilation (check fans, remove dust), bad power supply (measure voltages with a scope when under load, too much ripple ? voltage drift ?)

It may be cheaper and much quicker in the long run to get a new machine than having to fix this one at knife point. Minimum downtime and some hardware to play with.

Is it running out of disk space?

Centos should have sar - that should show you the progression of any problems.
High loadavg could be lots of tasks being spawned, or lots of outstanding I/O. One would suspect the latter, but with mysql, who knows.
I'd be betting on the I/O, and swap activity being driven up - all apparently against just the one disk.