[ Thanks to Doctor
High for this link. ]
“When I build a network or a system, I try my best to make sure
that everything is as redundant as possible: redundant power
supplies, RAID for the drives in case of a hard drive failure,
backup routes in OSPF in case someone trips over the network
cable… you get the idea. But what happens if the CPU overheats in
one of the web servers and causes it to crash? Or what if someone
yanks the network cable from your LDAP server? Or if someone flips
the switch and accidentally turns off the accounting database
server? If you incorporate High Availability (HA) into your system
design, the answer is ‘nothing.’ Your web site will still be
running, your network users can still login, and the accounting
department won’t notice any glitch. You don’t even have to leave
your desk…”