Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!zaphod.mps.ohio-state.edu!ncar!ico!rcd From: rcd@ico.isc.com (Dick Dunn) Newsgroups: comp.unix.i386 Subject: Re: 2 hardrives of different interfaces allowed to coexist? Summary: miscellaneous notes Message-ID: <1990Aug21.235008.13039@ico.isc.com> Date: 21 Aug 90 23:50:08 GMT References: <1990Aug19.182733.8095@uicbert.eecs.uic.edu> Distribution: comp Organization: Interactive Systems Corporation, Boulder, CO Lines: 44 teoh@uicbert.eecs.uic.edu writes: > Is it possible to allow 2 different types of hard disks in a pc UNIX > environment (using 2 different controllers)? If so, what are comments > on AT IDE vs ESDI drives? It is possible to mix controller types, as long as you apply the care you'd expect, to avoid interrupt and I/O port conflicts. IDE and ESDI are both fairly inexpensive ways to get disks a bunch faster than old AT ST-506 (MFM) drives. IDE is usually cheaper; IDE drives tend to be smaller. >...Is it true to say that the AT IDE drive is dependent on AT architecture > machine?... Yes, in the sense that the "IDE" interface is mostly a way to extend the relevant parts of the "ISA" (AT) bus. That's not to say you can't make an IDE controller for some other bus; it's just that IDE is most closely matched to ISA. The win with either IDE or ESDI--or, to look at the other side, the loss in the old ST506 interface--is that the old style has a separate drive and controller with a rather slow interface between the two. It is this interface (which is standard) that limits the data rate. ESDI keeps the drive/controller split but ups the data rate. IDE puts the controller on the drive; the maximum IDE data rate is determined by the ISA bus. One thing to keep in mind about IDE: The interface matches that of a primary disk controller on the AT bus, and you get a max of two IDE drives. After that, to add more disks you'd have to add them on a "secondary" AT-style controller (standard or ESDI) or SCSI. > I was planning to use the slower 80MB as secondary drive for back up > purposes or storing files of lower priority, and leaving all the executables > in the faster drive. Will there be any substantial loss of performance w/ > this configuration?... Performance shouldn't be that much of a problem--just move things around if the slow disk is getting too much use. Even staying with a slow disk, you can improve performance if you've got an old 2:1 or 3:1 controller by going to a 1:1 controller. These are in the neighborhood of $100. -- Dick Dunn rcd@ico.isc.com -or- ico!rcd Boulder, CO (303)449-2870 ...Are you making this up as you go along?