[Gllug] best way to update a single production server?

[Khusro Jaleel]

Hi everyone,

We have a very important production server that needs updates (just
simple Debian Etch updates, not Etch to Lenny). There are several
updates, including kernel and other updates, etc.

Since unfortunately we have only this server, and it MUST be up 24/7,
I'm not sure how to apply these updates, since a reboot is needed.

Some suggestions have been:

1. Ask the DC to transparently re-route the IPs on that server to
another server, run the website from there. Then, apply updates to
original server, reboot, and point things back.
2. Change DNS for the website to somewhere else for a few days
(depending on TTL), update/reboot, then change DNS back.
     - I have been told that this will be tricky because not everyone
respects TTLs, allegedly AOL servers will keep the old IPs for upto 2
weeks! I'm not sure if this is true or not.
3. Setup another server that just shows a maintenance page and point
the main website to that, then we can update and reboot and point
things back.

In the longer term, what is the proper way to manage this process? Do
you guys always install 2 servers in some sort of HA config so that
while 1 is being updated, the other one takes over?

Or do you use load balancers like F5 BigIP that handle this for you?

Another option might be to use VMs? So we setup each server with 2
VMs, so while we update 1, the other one takes over, but uses the same
IPs?

Thanks for any insight.
Khusro
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