[CentOS] Back-up connection

[Devin Reade]

For remote power management (including when I'm on-site and want to do
it from my desk instead of the server room), I use PDUs (power distribution 
units) like
<http://www.apc.com/products/resource/include/techspec_index.cfm?base_sku=AP7900>
(which is also an excellent fencing device if you're doing clustering).
They may be expensive for a hobbiest, but for a business using tested
commercially available hardware configurations should be a no-brainer.

If you have an OOB (out-of-band) way of getting to that network, just make
sure that the PDU is reachable via OOB.  Now a days I tend to use a
connection via an alternate provider (so if you're using ADSL, maybe
there's a cable provider in the area as well).

If you want to go old school, you can hook a modem directly to the AP79xx
serial control port, however if you're going to deploy a modem I'd suggest
hooking it up to an internal server and then ssh/telnet to the PDU from that
server; that way the modem is able to help you in other network-not-available
cases.

If an OOB connection is not feasible, then your only other option is
what others described: Write a script to check connectivity to upstream
services (I'd use at least three instead of just one), and trigger the
PDU reset if they fail.  Perl and various CPAN modules make this easy
(although doing it this way would be my last choice compared to an
OOB connection).

Devin
-- 
Yield to temptation; it may not pass your way again.
							- Robert Heinlein