[Discuss] Redundant array of inexpensive servers: clustering?

[blu at nedharvey.com (Edward Ned Harvey (blu))]

> From: discuss-bounces+blu=nedharvey.com at blu.org [mailto:discuss-
> bounces+blu=nedharvey.com at blu.org] On Behalf Of Rich Braun
> 
> My goal is simple:  mash the power button or yank the network cable from
> either of these machines, and have all the apps still running.  Then plug the
> machine back in and have all state restored to full redundancy without having
> to type any commands.

Hehhehe - No.  The goal is mash the power button, with the results described above, while using only 2 servers and free software.   ;-)   Which is considerably tougher.

In a commercial environment, I know you can use shared highly redundant storage (I don't want to say SAN, but essentially SAN).  And vmware can keep the brains in sync across multiple heads, but you have to pay.

In a minimalist environment, the only thing I know that can keep storage in-sync across two nodes without a 3rd quorum, is drbd (and similar solutions on other OSes) but this will only give you hot-cold replication.  You could easily script a watchdog, and you could make assumptions like, "I'm only trying to quickly recover from a complete system failure," so if I'm up and the other guy isn't, then I will launch my VM.  etc.

Let us know if you find something better.