Regarding Memcached Server configuration?

[Dan Christian]

On 9/26/07, Marcus Bointon <marcus at synchromedia.co.uk> wrote:
> We are using the latest PHP memcache client which implements consistent
> hashing strategy.
> If you are only running one server, you might be better off using APC for
> your caching. If you have 2 servers, you might get better performance by
> running your PHP on both, and also using both for memcache (with memcache
> the more physical servers you have, the faster it can go, on average). This
> will also give you a bit of redundancy, letting your service continue if one
> server dies.

I'm a bit confused about the redundancy aspects of memcached.  My
understanding is that you can have multiple memcacheds, but they store
different objects (based on the keys).

Tell me if I understand this right.  If I run a memcached on each of 2
machines, then the failure of a machine takes out half the cached
objects.  These values will continue to be un-cached until that
machine is removed from the client's configuration.

Is there an automatic recovery mechanism?
Is there a (big) performance hit when the configuration changes?

-Dan C