Path: utzoo!utgpu!watserv1!watmath!att!pacbell!pacbell.com!mips!zaphod.mps.ohio-state.edu!sol.ctr.columbia.edu!ursa!jawitz From: jawitz@ursa.UUCP (Eric Jawitz) Newsgroups: comp.sys.ibm.pc Subject: Disk interleave. Keywords: interleave disk spinrite Message-ID: <4627@ursa.UUCP> Date: 4 Jun 90 15:28:17 GMT Organization: Bear Stearns, NY Lines: 41 writes - >Don't forget to ask for 1:1 interleave for the controller card !. >I had some experience to purchase computer(s) from CompuAdd, they >usually give us 3:1 or 2:1 if we didn't ask. I'm curious to know what a 1:1 interleave disk controller card does for performance. I have two 40 meg. Seagate (ST 251-1) drives in my 386/25 system on which I recently ran SpinRite which supposedly optimizes the disk interleaving. SpinRite reported that the interleaving was set at 3:1 (yielding about a 176K/sec. throughput) and that the optimum interleave would be 2:1 (resulting in a 50% greater throughput). So I let SpinRite do its stuff and change the interleaving. The Norton SI disk index shows no change in performance between 3:1 and 2:1 disk interleaving (both yield an index of 2.6). I assume this is because SI does not measure throughput to derive the index. On the other hand, the Checkit disk benchmark shows a throughput of about 250K/sec. with 2:1 compared with 176K/sec. with 1:1. It seems, therefore, that SpinRite did make a difference. The talk about a 1:1 interleave disk controller puzzles me because if the interleave can be changed with software, what's the need for a special controller card? How is a 1:1 controller any different from my (apparently) 3:1 controller? Should I consider getting one? On a related note, my system has a selectable bus speed (8/12 megahertz I believe). I realize that some cards may not work at the higher speed. However assuming that everything checks out OK, are there any drawbacks to increasing the speed? Would the system run hotter? Would I be shortening the life of my boards? Am I likely to see an increase in disk throughput? Is this in turn likely to affect the optimum interleaving for my system? If you have insights into any or all of the above questions, I'd be most grateful to hear from you. -Ed Thieberger beareq!thieb@wheaties.ai.mit.edu