--- Desert Fox <[EMAIL PROTECTED]> wrote: > What's the secret to getting 80 pin SCA SCSI HDs to > run full speed ahead? I > got a couple of Seagate Cheetah 10K rpm drives that > are DOGS on every SCSI > bus I've tried them on. Is it the adapters (either > 68 pin wide or 50 pin) > that is the bottleneck?
Have you tried them with something like a Jackhammer wide SCSI card? I don't know if one of those would be fast enough on NuBus. The problem you're seeing is overshoot. The drive is so fast that the SCSI controller in the computer can't accept data as fast as the drive can deliver it. The Mac gets one sector of data but by the time it's ready for the next one, the next one has gone by, possibly more than once, so the Mac has to wait for it to come around again while it waits to catch it. It's the same problem the Plus and SE had where for the average drive of the day, the Plus needed a 3:1 interleave and the SE needed a 2:1 interleave. Interleave spaces out the sector IDs so that the Mac can read them in order. Several sectors will pass by as the Mac is processing one, then the next in line shows up just as the Mac is ready for it. The problem is I don't know of any apps that can handle formatting large drives with other than 1:1 "interleave", which isn't interleaved at all. Unless FWB Hard Disk Toolkit can do it. SCSI Director 1.7.2 has a 3:1 button for Mac Plus, a 2:1 button for Mac SE and a 1:1 button for Other, but I doubt it can format anything over 2gig. Hmmm, I wonder if a PC with a good SCSI controller can come to the "rescue" here? I'd have to take a look at my Adaptec 2940 Ultra/Wide controller's BIOS and see if it has an interleave option for low level formatting. It'd take a while to hit the best setting for speed, starting with 2:1 then 3:1 and going higher until the sweet spot is found. The time would come from having to totally reformat the drive every time. Hmmm, I should try that with the 18 gig SCA drive I have on my Radius 81/110, which *should* be able to run at the maximum bandwidth the SCSI bus is capable of, which *should* be fast enough for video capture from the Media 100, but is not. ===== Say hello to Juror #49. Yep, I'm on jury duty until the end of March. Gotta call in each weekend. Fun. __________________________________ Do you Yahoo!? Yahoo! Mail SpamGuard - Read only the mail you want. http://antispam.yahoo.com/tools -- Vintage Macs is sponsored by <http://lowendmac.com/> and... Small Dog Electronics http://www.smalldog.com | Enter To Win A | -- Canon PowerShot Digital Cameras start at $299 | Free iBook! | Support Low End Mac <http://lowendmac.com/lists/support.html> Vintage Macs list info: <http://lowendmac.com/lists/vintagemacs.shtml> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive: <http://www.mail-archive.com/vintage.macs%40mail.maclaunch.com/> Using a Mac? Free email & more at Applelinks! http://www.applelinks.com
