RE: Server Redundancy

["John Ferriby" <john () ferriby com>]

Rob Pickering said:

> I've used both the route hack based and commercial NAT load 
> balancers, and they both have their place.

Yes, one size does not fit all.
 
> Commercial NAT based load balancers are able to do things like 
> distribute requests according to actual measured server response 
> characteristics. This is great if you have clusters of servers with 
> different specs but want to extract the best performance under peak 
> load from the whole cluster. It also helps if you are running complex 
> services where individual servers can develop a pathological slow but 
> not failing response for some reason.
>
> They are also able to do the kind of service polling as above and 
> react quicker to a down server than one which relies on routing 
> protocols.

Quite true.   A product not mentioned in previous posts would be the
Radware WSD, which has been great for my applications.  See it at
www.radware.com   These come in distrubted flavors too.

Also not mentioned previously would be the Netscaler, www.netscaler.com 

> If you are running complex web services (think expensive per server 
> sw licences etc) then the investment in a pair of redundant load 
> balancers for the front end to give more consistent performance under 
> load as well as resilience can look very sane indeed.

Oh, yes.   They make a lot of sense in large streaming environments.

-John