Last month I wrote about how users were discussing switching over to compute farms with nests of Big Iron CPUs at their collective beck and call from PCs acting as dumb terminals. An advocate of that change, Alain Raynaud from the Meta Systems division of Mentor Graphics, closed that discussion by warning, "Any downtime and your whole department is on holiday. But it's so much easier to administer, too. But I'm not saying it's cheaper (it probably isn't). Another drawback is upgrading. A powerful configuration today will seem low-end in one year. It's easier to replace workstation after workstation, but changing your one big iron is not always so cost-effective. Try to negotiate a good upgrade deal."

Now, since that column was published, users have been pelting me with e-mail (which I love) with "the rest of the story" as they see it.

Giri Iyer of Compaq wrote, "Do not sign an upgrade deal! I strongly recommend the use of LSF Suite from Platform Computing to cluster together workstations and PCs. There is practically no downtime. Lose a CPU, you are fine. Lose an entire workstation/server, your job will automatically fail-over onto another CPU on the compute farm. Need more CPUs? Just keep adding them as required. Want to get rid of your older systems? Just retire them. LSF suite works across different O/Ses, allowing you to protect your current Unix investment while allowing you to add more cost-effective NT hardware gradually into your cluster. (This also partially puts an end to the religious debate of Unix vs. Linux vs. Windows NT, etc., and lets us focus on better designs.) At Compaq we now have a 100+ CPU farm of Intel/NT-based Compaq Professional Workstations for our ASIC simulation, along with our 60 CPUs of Sparcs and Sparc clones."

From the U.K., John Biggs of ARM inadvertently agreed with Giri by writing, "We have been managing a cluster of powerful Sparcs ("virtual mainframe") with Platform Computing's LSF load-balancing and job-scheduling SW for over a year now. I have to say it works very well. Some people drive the Sparc Farm from older, lesser Sparcstations, but most choose to use a PC as they get access to MS Office (gak!) and also a 1,600 x 1,200 desktop. It is also easier to manage when you need more licenses/CPU by looking at the depth of the queues and the turnaround time. It often makes more sense to buy faster machines than more licenses."

And a buddy from Cisco Systems anonymously chimed in with, "Overall, I don't think I can say enough good things about LSF-but don't tell them that, they'll just want to raise their prices."

— John Cooley runs the E-mail Synopsys Users Group (ESNUG), is a contract ASIC designer and loves hearing from engineers at jcooley@world.std.com or (508) 429-4357.