[Mongrel] [Slightly OT] Do you use virtualization in production ?

Scott Laird laird at google.com
Tue Oct 3 20:04:53 EDT 2006

On 10/2/06, Luis Lavena <luislavena at gmail.com> wrote:

> Ezra, one thing that still bug me is IP handling. If i have a live
> server and decide to do a hot migration to a newer box, how it
> manages, and how much downtime will get to the IP switches ges
> notified of the migration? (in ms resolution)
> Or i'm forced to have a load balancer that handle the problem for me?

If you're doing it right, the switches should notice within a few
milliseconds.  Any reasonable virtualization setup will have to assign
a virtual MAC address to each virtual ethernet interface, and the MAC
address should transfer between machines along with the rest of the
VM.  So, assuming that both machines are on the same L2 network, it's
just a matter of the new machine sending an Ethernet frame or two out
its interface using the virtual MAC address as the source address.  To
the switch, it'll look like the virtual server was unplugged from one
port and plugged into the new one, which isn't a big deal.  I'd be
amazed if VMWare didn't have code in it to explicitly trip this, but
even without it it'll happen almost instantly.


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