Joe Landman <[email protected]> wrote: > I am arguing for commodity systems. But some gear is just plain junk. > Not all switches are created equal. Some inexpensive switches do a far > better job than some of the expensive ones. Some brand name machines > are wholly inappropriate as compute nodes, yet they are used. > > A big part of this process is making reasonable selections. > Understanding the issues with all of these, understanding the interplay.
A lot of this issue boils down to a lack of available information, or perhaps, the cost of obtaining the information. Consider for instance the switches you cited above. How is the average site going to decide which switch is better before purchase? On paper, going by the published specs, they will often look identical. The two companies may be equally reputable. Still, one device may be a piece of junk and the other best in class. On very rare occasions there will be an independent review available. Only a large site is likely to have the resources to obtain samples of each switch and test them extensively. The best most of us can do is ask around if "switch XYZ is OK" before making the leap. With compute nodes performance information is more readily available, often in reviews, but again, rarely any reliability information. And we have all seen models which crunch nicely but have innate reliability problems that don't turn up in a 3 day review, and then bite hard during continuous use. Again, large sites can obtain a test unit and beat on it for a few months, but small sites usually cannot. At least in this case knowledge does build up over time in the community, so if one waits for a machine to be in the field for a year, it may be possible to ask around and find out if it is a good idea to buy some. (But don't wait too long, the sales life for computer models is not very long!) For this reason, unless a site is very well funded, buying cutting edge compute nodes is a rather large gamble. If the resources to run these tests isn't present in house, one may essentially buy the expertise by paying enough to a reputable company to run the tests. Either way, knowing costs money. Ideally there would be accepted standards for testing performance and reliability of each class of equipment, and the manufacturers would run these tests themselves, or farm it out to neutral entities, and then publish this information. It would certainly be a compelling sales tool, at least from my perspective. In practice, it usually seems like the manufacturers spend more time hiding equipment defects than they do in proving and publishing its strengths. Regards, David Mathog [email protected] Manager, Sequence Analysis Facility, Biology Division, Caltech _______________________________________________ Beowulf mailing list, [email protected] sponsored by Penguin Computing To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
