[erlang-questions] Why is Erlang what it is?

[Mats Cronqvist]

Dominic Williams wrote:
> if we can do soft upgrade well, why bother with 
> redundancy upgrades...

   we do have to handle redundancy... it's not much extra work to add redundancy 
upgrade.
   the killer is of course that you will eventually have to upgrade the emulator.

   otoh, i believe you probably could soft upgrade a pure erlang system of any 
size, but only if it was designed for that from day one (all code must be 
prepared to accept data in the pre-upgrade as well as post-upgrade format).
   of course, as ulf points out, you almost never have a pure erlang system.

   to summarize my personal experience; if you're aiming for 100% availability, 
you must have redundant hardware and handle failover, and then redundancy 
upgrade will be your best bet.
   of course, being able to load small patches on the fly is pretty priceless.

   mats