lon.leader@canremote.uucp (LON LEADER) (07/16/90)
Can anyone tell me how to 'set' or 'force' a specific interleave when low-level formatting a harddisk on the 3000? Here's why I want to do this. I have just moved up to a 3000 from a 1000. On the 1000 I was using a 80 meg. MFM disk with an Adaptec 5500 MFM to SCSI interface and a Comspec controller. This setup was not fast, but it was better than floppies. Tests revealed the optimum interleave for this combo was three, yielding a DiskSpeed 3.1 rating of approx. 130-140,000. I plugged this drive/interface into the 3000 and did not low-level format it (in a failed attempt to retain the data on the drive). I partitioned the drive and did an AmigaDOS format. DiskSpeed gave a 172,000 rating on this. I then used the 3000 to do a low-level format and the drive now tested out at 253,000. I figured from this that the interleave had been set lower than the three it was before, but I had no way of knowing what it was. I hooked the drive back up to the 1000, and low-level formatted it with an interleave of two, then moved it back to the 3000 for partitioning and testing. I got an identical 253,000 rating, so I guessed that the interleave arbitrarily choosen by the 3000 software was two. Mad impetuous fool that I am, I then moved the drive back to the 1000, and low-leveled it with an interleave of one. Back on the 3000 for partitioning and testing, I got (are you ready for this?) 436,000 !!!! It isn't as fast as the Quantum inside (612,000) but I like it. It has worked without any problems for several days. Now, does this mean I have to keep my 1000 and Comspec around just in case I ever want to low-level format this, or another drive? And the question that keeps nagging at me is, what is the interleave on the internal Quantum? Maybe it is only two, and would scream if I could lower it to one? -=[ Lon ]=- lon.leader@canremote.uucp --- * Via ProDoor 3.1R
jesup@cbmvax.commodore.com (Randell Jesup) (07/24/90)
In article <e42ea82e443226a16398@canremote.uucp> lon.leader@canremote.uucp (LON LEADER) writes: > > Can anyone tell me how to 'set' or 'force' a specific >interleave when low-level formatting a harddisk on the 3000? ... > I then used the 3000 to do a low-level format and the drive >now tested out at 253,000. I figured from this that the >interleave had been set lower than the three it was before, >but I had no way of knowing what it was. ... > Mad impetuous fool that I am, I then moved the drive back >to the 1000, and low-leveled it with an interleave of one. >Back on the 3000 for partitioning and testing, I got (are you >ready for this?) 436,000 !!!! It isn't as fast as the Quantum >inside (612,000) but I like it. It has worked without any >problems for several days. When HDToolBox (or the production prep program) formats a SCSI drive, they request interleave 0, which is SCSI shorthand for asking the controller to select it's favorite interleave (since the drive in most cases knows more about the best interleave than HDToolBox does). It sounds like the Adaptec thing is selecting 2, when it can run faster at 1. Perhaps Adaptec thought that the hosts it would talk to would be too slow to deal with 436K/s (and on a PC clone, they might be). All modern drives I've tried have selected interleave 1. Ability to set interleave was considered, but was deemed a bit too confusing for most users, especially since almost all drives select the "right" numbers. Perhaps this can be worked into some advanced options stuff for a future release. -- Randell Jesup, Keeper of AmigaDos, Commodore Engineering. {uunet|rutgers}!cbmvax!jesup, jesup@cbmvax.cbm.commodore.com BIX: rjesup Common phrase heard at Amiga Devcon '89: "It's in there!"