Re: successful migration from client/server to 3 tier systems ?

Casey Green wrote:
>
> # Microsoft has been posting some phenomenal numbers
> # (like 5676 tpm-c under a simulated load of 5000 users) without
> # the aid of a TP monitor. It seems to me that the claim that
> # 2-tier doesn't scale is starting to look awfully thin.
>
> Now, I don't like to dispute the merits of Microsoft's
> technology. So let's say that those numbers are bona fide.

  So far as I know, no one has suggested that cooking the TPC-C benchmark is even posssible. It's a very involved benchmark that simulates the operations of a bank branch.

>
> Now let's see a show of CIO hands who'd be willing to put
> their paychecks on the line to implement a real system
> expecting these numbers. Next, a show of senior engineers'
> hands who'd put their paychecks on the line to work
> on that project.

  I think you've misunderstood my point. Obviously someone who designs a system expecting every component to perform at the level it did during a benchmark is nuts; it doesn't follow that these results don't shed any light on the question of two-tier scalability. Nowadays consultants and other assorted gurus are routinely specifying 3-tier architectures for projects that will never get within shouting distance of these numbers. The last four projects I've worked on have all been three tier, and all but one are never expected to be deployed to more than 150 users. Nevertheless, the most commonly cited reason for going three-tier is that "two-tier doesn't scale." Well, I think it's pretty clear from results like these that 2-tier scales pretty well. I wouldn't have any qualms about specifying a 2-tier architecture for, say, 1000 users-- a figure which I'd guess 80% of today's 3-tier projects will never reach. The added costs of implementing a system as 3 tier are, in my experience, enormous: the available tools are not nearly as mature as the best of the currently available 2-tier products. That is rapidly changing, as everybody scrambles to jump onto the three-tier bandwagon, but it will continue to be true for the next year at least. Received on Mon Aug 12 1996 - 00:00:00 CEST