neese@adaptex.UUCP (10/11/89)
<<STUFF DELETED >> >The WD series also has better ECC capability demonstrated on the >bench, it can recover data from marginal drives that the Adaptec will error >out on. As an example, we have one ST4144 right here in the shop that shows >~30 errors with our diagnostic software using the WD1006, and some 200 (!) >errors on the >same< drive using a 2372. This is a shop drive; I'd never >put that thing in a box for a customer, but it does demonstrate the superior >data recovery abilities of the WD card. Adaptec claims to have the best >data separation capability; they're full of hot air. Our actual field tests >don't bear out their claims. > >You know which board I'm going to trust my data to given a choice, don't you? Well, I don't want to start a flame war here, but here are some facts about both controllers. 1) By default, the 2372 does zero retries to get data from a device. The WD controller does 8 retries no matter what. The 2372 does not do retries unless the system it is running in requests them. This alone will account for the difference in errors. 2) The data separator has nothing to do with errors that are witnessed at the BIOS level. Errors at the BIOS level are usually due to ECC failure after all retries have been exhausted. If the system does not setup retries, as per the AT specs, then an immediate failure will be reported by the 2372 after only one ECC pass on the defective data. 3) If you would like to take our data separator and bench test it off of the controller, you will find it meets the specs. In meeting the specs it does a better job than the comparable specs for the WD data separator. I will not challenge the performance differences as I haven't tested them out, but as far as the rest of your claims, they are full of hot air. If you would like to discuss this further, then E-mail me, as I think this kind of talk is more bandwidth waste than anything else. Oh, by the way, to let you know, I have about 10 years of mass storage evaluation experience. Roy Neese Adaptec Central Field Applications Engineer UUCP @ {texbell,attctc}!cpe!adaptex!neese merch!adaptex!neese
karl@ddsw1.MCS.COM (Karl Denninger) (10/12/89)
In article <6700027@adaptex> neese@adaptex.UUCP writes: > ><<STUFF DELETED >> >>The WD series also has better ECC capability demonstrated on the >>bench, it can recover data from marginal drives that the Adaptec will error .... >>You know which board I'm going to trust my data to given a choice, don't you? > >Well, I don't want to start a flame war here, but here are some facts about >both controllers. >1) By default, the 2372 does zero retries to get data from a >device. The WD controller does 8 retries no matter what. The 2372 does >not do retries unless the system it is running in requests them. This alone >will account for the difference in errors. Unless retries are disabled. Which our bench software does. And it does not use the BIOS (we have that turned OFF in both boards in production systems, remember, this in a Unix (actually Xenix) machine!) >2) The data separator has nothing to do with errors that are witnessed at the >BIOS level. Errors at the BIOS level are usually due to ECC failure after >all retries have been exhausted. If the system does not setup retries, as >per the AT specs, then an immediate failure will be reported by the 2372 >after only one ECC pass on the defective data. See above. The BIOS is not used in a protected mode operating system after the boot sequence completes. In our case we have it jumpered out anyway. >3) If you would like to take our data separator and bench test it off of the >controller, you will find it meets the specs. In meeting the specs it does >a better job than the comparable specs for the WD data separator. Ok. So? This isn't a "your chip is better than my chip" fight. It is a test with real data, on real disk drives, under real-world use conditions. Advertising and technical claims are puffery. Real-world experience is what counts, and we have it with both controller boards in >exhaustive< tests. I have one drive here, the above-mentioned ST4144R, which is somewhat flaky. It came out of a machine for exactly that reason -- it wasn't reliable. The ACB board can handle it, sure, but it shows more errors on our bench test set than with the equivalent WD card (1006VSR2). Whether due to retries or not is not the issue; what IS at issue is the performance the user sees under real-world conditions. >I will not challenge the performance differences as I haven't tested them >out, but as far as the rest of your claims, they are full of hot air. It would be wise of you not to challenge the performance claims. They are based on simple tests that anyone with a Xenix system can duplicate. To whit: Test on a quiet system (I just performed it again): dd if=/dev/rxxxx of=/dev/null bs=4k count=1000 (xxxx is the device name, "r" for raw device) SCO Xenix 2.3.2 Operating System Adaptec ACB2372 WD1006V/SR2 real 39.64s 11.38s user .20s .08s sys 2.56s 2.46s KB/sec 103.329 359.929 Both systems identical except for controller and drive. Both drives formatted at 1:1 interleave. The Adaptec doesn't have a track cache, while the WD1006 does (I can see the RAM chip part number on the WD board, it is obvious) > Roy Neese > Adaptec Central Field Applications Engineer I'll also note that Adaptec said "tough beans" when we had problems with random hangs on the controllers (which turned out to be a problem between the ACB2372s and the ST4144 series drives -- a compatibility issue that has not arisen with other controllers -- you need to insert J6 on the ST4144Rs IF AND ONLY IF you have two drives connected). They didn't even want to talk to us and it took several hours to get through to on their technical support line. WD, on the other hand, was reached with 1 call the last time I had a question. The >only< advantage I have seen with the ACB2372s is that Adaptec was thoughful enough to provide a "secondary IRQ" jumper block. WD doesn't do that, which has been the subject of complaint by our organization. We'll see if they respond to it. If our ACB2372 boards are defective I'll be happy to exchange them with Adaptec and realize the "greater" performance capabilities of the card. So far that offer has not been made. -- Karl Denninger (karl@ddsw1.MCS.COM, <well-connected>!ddsw1!karl) Public Access Data Line: [+1 312 566-8911], Voice: [+1 312 566-8910] Macro Computer Solutions, Inc. "Quality Solutions at a Fair Price"