Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!pyramid!octopus!pete From: pete@octopus.UUCP (Pete Holzmann) Newsgroups: comp.sys.ibm.pc Subject: Re: big disks on PC AT clones Message-ID: <205@octopus.UUCP> Date: 29 Apr 88 18:30:08 GMT References: <21346@amdcad.AMD.COM> Reply-To: pete@octopus.UUCP (Pete Holzmann) Organization: Octopus Enterprises, Cupertino CA Lines: 169 Summary: I just investigated this; here's some answers (LONG) In article <21346@amdcad.AMD.COM> phil@amdcad.AMD.COM (Phil Ngai) asks about big drives, big partitions, and fancy disk manager programs. I've been looking at all this a lot recently. Here's some answers: [By the way... this article is Copyright 1988 by Octopus Enterprises. You may use this information in any way that you like, as long as it doesn't get republished without permission. I'm not charging you for the info, so please don't charge others for it either!] You CAN handle drives bigger than 32MB as long as you are using DOS 3.x (earlier versions of DOS didn't have a big enough FAT table to make it practical). You CAN have partitions bigger than 32MB as long as you don't use some of the low-level hard drive interface programs that assume a normal (2K) cluster size. PC Tools, for example, gets sick on partitions bigger than about 160M. The (amazing, wonderful, etc) new 'SpinRite' program that optimizes low-level formats can't handle partitions >32MB in its current version. Norton seems to be OK. CHKDSK can get sick. What are the pieces of the puzzle?.... BIOS: Doesn't directly support drives >1024 cylinders, thus requiring special device drivers. The 'Setup Drive Type' table imposes limitations on wasted disk space vs. your boot partition (see below). The BIOS generally doesn't care two hoots about partition size. DOS: Except for custom versions (Toshiba and Compaq), no version of MSDOS supports partitions bigger than 32MB. No (standard) version of DOS prior to 3.3 directly supports multiple 32MB partitions on a single drive. CONTROLLER: # heads and # cylinders supported is limited by the controller. Some controllers have special support for large drives. E.g. OMTI and Adaptec have built-in low level formatting, and partitioning into N 32MB partitions. OMTI makes itself look like lots of separate drives. Adaptec loads a special driver into your boot partition; the driver then takes care of telling DOS about the extra partitions. SPECIAL DEVICE DRIVER/PARTITIONER: These things have several functions, some of which could be accomplished in other ways, some of which need the special software: a) Low level format (usually doable using debug & controller firmware) b) Override 'Setup drive type' table. (generally unique) c) Fancy partitioning, e.g. >32MB partitions (generally unique) d) High level format (also can be done using DOS FORMAT command) e) Intense surface test of drive (also doable with other purchased software) What are the limitations? Let me outline them in some kind of category sequence: BUCKS: In general, you'll end up spending a nice chunck of change ($50 or more) on a 'disk partition manager' program in order to deal with big drives and/or big partitions. Why so much bucks? Because the programs are necessary, they are NOT a mass- market item, and they are easily pirated. There are some exceptions: a) If you just need to handle big drives, but don't need big partitions, you have a few low cost choices: 1) Use DOS 3.3. It handles lots of 32MB partitions on a single drive. Downside is that 3.3 is a memory hog (and typically costs a little more than 3.2 anyway). 2) Use an RLL drive and an Adaptec RLL controller (e.g. 2372 HD/FD controller). You pay maybe $70 extra for the controller, but you get 50% more disk space, 400% more throughput (700K/sec), and the controller firmware is able to download a FOO.SYS partition manager driver onto your boot partition (nice trick!) b) If you are buying a Seagate drive, the drive usually comes with a custom version of Disk Manager included. First partition must be <=32MB, but other partition(s) can be >32MB. BIOS PROM LIMITATIONS: If your BIOS doesn't have a drive table entry that supports a drive with a) # Cylinders <= # Cylinders on your drive b) # Heads <= # Heads on your drive then you need a new BIOS. The problem is that the startup test will crash and burn because it can't find the whole drive listed in your setup parameters. If your BIOS doesn't have a drive table entry that supports a drive with a) # Cylinders <= # Cylinders on your drive b) # Heads EQUAL TO # Heads on your drive (*note* above was <= ) then your boot partition is going to waste some potential disk space. The boot partition can only use heads listed in the BIOS drive table. For example, if your drive has 18 heads, your setup params drive has 4, and you make a 10 MB boot partition (C: drive), you'll have 10MB of wasted space (heads 4-7 on the first cylinders of the drive). GENERAL BIOS LIMITATION If your drive has more than 1024 cylinders (e.g. Maxtor 1140, 2190, etc), it gets very interesting. INT 13 in the BIOS does not support more than 1024 cylinders. So what to do?.... a) Use an OMTI RLL controller and SpeedStor b) Buy your drive from Storage Dimensions (makers of SpeedStor and a subsidiary of Maxtor); they'll give you a souped up version of SpeedStor that handles >1024 cylinders on just about ANY controller. [*flame*- is bundling like this legal? I thought that bundled software also had to be made available separately at a reasonable price!] c) Buy the generic version of Disk Manager along with their 'SuperProm' extended BIOS drive table [$100 for two PROMS. Yech.] [They are working on a new version of Disk Manager that doesn't need the extra PROMS. It'll be ready Real Soon Now]. d) Buy Vfeature Deluxe from Golden Bow ($110 or so) BOOT PARTITION SIZE LIMITATIONS Almost all known large-drive-handling methods require the boot partition to be <=32MB. The exception is Vfeature Deluxe, which claims to allow the first partition to be huge if you want. I've got a copy coming in early next week; we'll see.... In addition, under many circumstances [seems somewhat random so far], many disk-partition-managers/DOS versions/??? require the boot partition on a large drive to be bigger than 16MB or you won't be able to boot from the hard drive. Has something to do with FAT table sizes. Someday I may understand this problem better, but for now suffice it to say that you may end up making the boot partition bigger than you would otherwise like. OTHER LIMITATIONS The Seagate version of Disk Manager isn't flexible enough to work with most RLL controllers. I've tried Adaptec and OMTI. Haven't tried Western Digital. The problem is that most RLL controllers steal the last cylinder for their own use, so a nominally 820 cylinder drive looks like it has 819. This drives DM crazy. OMTI controllers steal 1K at the end of your 640K (so you end up with 639K). This makes EEMS backfill impossible on '286 machines. On '386 machines, if you get "386 to the Max", they can send you a little routine that relocates the stolen 1K to low memory so backfill will work properly. RECOMMENDATIONS IF you are getting a Seagate drive and normal controller, use the free DM. IF you don't care about big partitions, use DOS 3.3 or an Adaptec controller and spend the saved bucks on your sweetie. IF you are getting an OMTI controller, get SpeedStor. They work well together. IF you are getting a < 1024 cylinder drive, SpeedStor works and is cheap. IF your boot partition must be big, or your drive is > 1024 cylinders, get Vfeature Deluxe [tentative recommendation based on lengthy talk with their tech support; I haven't tried it yet]. Tech support experience: GREAT: SpeedStore, Disk Manager, Golden Bow. OK: [slow to answer, limited hours] Adaptec. NOT OK: [had to wait for callback several times] OMTI. -- OOO __| ___ Peter Holzmann, Octopus Enterprises OOOOOOO___/ _______ USPS: 19611 La Mar Court, Cupertino, CA 95014 OOOOO \___/ UUCP: {hpda,pyramid}!octopus!pete ___| \_____ Phone: 408/996-7746