--- Brad Wilson <[EMAIL PROTECTED]> wrote: > Brad Wilson wrote: > > > However, if you use Windows Load Balancing, my understanding is that the > > multiple machines all appear as one large, single machine to the outside > > world. > > My mistake. This is clustering, not load balancing. That'll teach me to > proofread before I hit send. ;)
You were right in the first place they do (kind of). Network load balancing redirects UDP/TCP/IP traffic to one of a group of servers. It works by sharing a virtual IP address, so from the perspective of traffic to that IP address they all appear as one big (virtual) server. It can support lots of machines, and is generally used for web server farms. Windows clustering service is, I believe, limited to 2 machines/nodes, although I recall something being mentioned about 4 in future. Generally it is run Active/Passive - one machine sits effectively turned off, one turned one. Should the active one fall over, the clustering service works this out and the passive one picks up all the load. They too share a virtual IP address, but the sharing more complex than NLB. The networking is only one aspect of the sharing. There is also Active/Active where both handle some load, but I can't recall from memory if Windows supports that yet. Importantly, Windows clustering service requires a shared SCSI disk (not very cheap as a rule). It is generally used for database servers, although there is no reason why you can't run a web server clustered, other than the expense. Peter __________________________________________________ Do You Yahoo!? Yahoo! - Official partner of 2002 FIFA World Cup http://fifaworldcup.yahoo.com You can read messages from the DOTNET archive, unsubscribe from DOTNET, or subscribe to other DevelopMentor lists at http://discuss.develop.com.
