cm@jet.uucp (colin manning) (04/24/91)
Until recently, I have been using a SCO Unix 3.2.0 system on which I also
use Windows 3 for which I have a DOS partition. When the system is reset,
I am presented with a menu that tells me to use F3 to boot DOS, F5
to boot SCO Unix, and F7 to boot from floppy. This is fine. I have not
wished to move this system to DOS 4, because I'm tight on memory under
DOS, and so the limitations in SCO Unix for handling larger DOS partitions
has not been a problem. This will be a different matter once DOS 5 is here.
I now have an ISC Unix 2.2.1 system as well, and need to have a similar
functionality with this system. Although it would seem possible to have
DOS and Unix to reside on the drive in different partitions, after reading
the manuals it would appear that switching from one OS to the other
necessitates using fdisk every time to change the active partition. This is
a bit long winded, and besides, fdisk is a somewhat dangerous program that
I dont want to have to use regularly.
This new system has a 1.2Gb drive, and I dont want to stick to the 32Mb
partitions that you are restricted to with DOS 3.3; neither do I really
want to use the 'extended partitions' of DOS 3.3 which allow you to
sub-divide an fdisk partition into several 'secondary' DOS partitions which
still have a 32Mb upper limit, because I will be switching to DOS 5 as soon
as its out so I can have >32Mb DOS 4 style partitions without the extra OS
memory overhead. Naturally I also wish to be able to mount DOS partitions
under both SCO and ISC, although neither SCO nor ISC supports the >32Mb DOS
filesystems at present.
Ideally, there would not be all these seemingly unnecessary restrictions
concerning support for different partition types, sizes etc. In my opinion,
whoever designed the fdisk partition table structure left a lot to be
desired - why only allow at most 4 partitions on a drive ? and why restrict
the cylinder numbers to 10 bits ? It seems to me that to have allowed a
reasonable number of partitions (say 32) and to use 32 bit disk addressing
would not have been too hard. The cost would have been, say, an additional
256 bytes or so to save a lot of hassle.
Also, why is it that support for DOS 4 partitions is non-existant in ISC and
SCO ? DOS 4 seems to have been around for quite long enough for support to
have been added.
Anyway, I'd be interested in information on any of the following. I'll
post a summary in due course if there's sufficient interest.
1. Is it possible to have an easy way of selecting between booting DOS
or Unix on an ISC system, without having to remember to use fdisk
every time to change the active partition ? Ideally the source to
a boot program that could be put on a primary DOS partition would
be nice (like the one I use with SCO).
2. Although ISC and SCO do not seem to have any support for >32Mb DOS 4+
filesystems:
i. When is support for these expected from ISC and SCO ?
ii. When you use SCO, and you interrupt the auto-boot to boot DOS (by
typing 'dos' at the : prompt), will it boot correctly off a >32Mb
DOS 4 partition ?
iii. If you try to have >32Mb DOS 4 partitions on a SCO or ISC system,
does the Unix safely ignore them even though they cant use them ?
3. Is it possible to have both SCO and ISC Unix on the same machine, in
different partitions, and have some way of selecting between the 2
at boot time ?
4. Does ISC recognise SCO partitions and vice-versa ?
Many thanks in advance,
--
- Colin Manning, cm%jet.uucp@ukc.ac.uk (world) OR cm@jet.uucp (UK only)
- Disclaimer: Please note that the above is a personal view and should not
be construed as an official comment from the JET project.jjr@rushpc (John J. Rushford Jr) (04/27/91)
In article <1991Apr24.074220.17639@jet.uucp> cm@jet.uucp (colin manning) writes: > >Anyway, I'd be interested in information on any of the following. I'll >post a summary in due course if there's sufficient interest. > >1. Is it possible to have an easy way of selecting between booting DOS > or Unix on an ISC system, without having to remember to use fdisk > every time to change the active partition ? Ideally the source to > a boot program that could be put on a primary DOS partition would > be nice (like the one I use with SCO). > I'd be interested in the answer to this for AT&T SVR3.2 also. I'm not too keen on using 'fdisk' to switch active partitions anymore. Recently I used DOS 'fdisk' to switch the active partition from DOS to UNIX. After re-booting I found that 30,000 blocks of free space had disappeared from the root filesystem. I'm not positive but, I suspect that DOS 'fdisk' had something to do with it. I could not fix it using 'fsck'. I poked around in the superblock with 'fsdb' but found nothing. I ended up reformating the disk and loading from backups. -- John ---- Westminster Colorado
urban@cbnewsl.att.com (john.urban) (04/30/91)
In article <1991Apr27.053546.1461@rushpc> jjr@rushpc.UUCP (John J. Rushford Jr) writes: >In article <1991Apr24.074220.17639@jet.uucp> cm@jet.uucp (colin manning) writes: >> >>Anyway, I'd be interested in information on any of the following. I'll >>post a summary in due course if there's sufficient interest. >> >>1. Is it possible to have an easy way of selecting between booting DOS >> or Unix on an ISC system, without having to remember to use fdisk >> every time to change the active partition ? Ideally the source to >> a boot program that could be put on a primary DOS partition would >> be nice (like the one I use with SCO). >> >I'd be interested in the answer to this for AT&T SVR3.2 also. I'm not too >keen on using 'fdisk' to switch active partitions anymore. Recently I >used DOS 'fdisk' to switch the active partition from DOS to UNIX. After >re-booting I found that 30,000 blocks of free space had disappeared from >the root filesystem. I'm not positive but, I suspect that DOS 'fdisk' >had something to do with it. I could not fix it using 'fsck'. I poked >around in the superblock with 'fsdb' but found nothing. I ended up >reformating the disk and loading from backups. >-- > AT&T UNIX System V/386 Release 3.2 Version 2.2 has a RAS add-on (Remote Administration something- or- some add-on like this). It has an altboot executable which toggles your boot partiton of your hard disk. Where as AT&T UNIX System V/386 Release 4.0 has 'altboot' built in to the code OS. When you see the prompt: Booting the UNIX System ... just press the space bar and type in: altboot and you'll boot from your MS-DOS partition instead of the UNIX partition. Sincerely, John Urban att!garage!jbu
rwhite@nusdecs.uucp (Robert White) (05/01/91)
I know that on the SCO system we have here you when you see boot : You can type "dos<cr>" and dos will boot. For my system at home <jagat> I have use the pfdisk program that was posted on the net some time ago. I still have the source archive (and I have compiled them for ms-dos but I never did get it to work from the unix side). The program works great! It replaces the harddisk boot sector program with one of two others. BOOTAUTO or BOOTMENU. BOOTMENU *always* gives you a menu of your partitions and you select the one from which you want to boot. BOOTAUTO will boot from the currently active partition unless you press a key within about 5 seconds of getting the "boot device h0" message; when you press a key you get the menu. I use AT&T SVR3.2.1(1) and MS-DOS 3.30a and BOOTAUTO. I have placed a timeout in the "save the dump space" question in the boot sequence so that my UNIX system will do a complete reboot unatended if the power goes out. When I need DOS I do a telinit 0, *HARDWARE RESET*(2) and a "<space>3"(3) at the prompt. What could be easier. If you need it (source or source and uuencoded binary for ms-dos) mail me at crash!jagat!rwhite (or rwhite@jagat cause I'm in the maps but the path there now just a tad longer than the direct method) and I'll send them out. (NO WARENTEES I didn't write it but it does work for me.) (1) Due to an oddity in the boot program for this release of UNIX System V the UNIX partition *must* be the active partition when booting. the boot program dosn't use dynamic boot information it gets the stats directly from the partition table. (2) Alwasy do a hardware reset when switching between UNIX and MS-DOS. There is no standard for software reset in a PC compatible system so a soft reboot may not properly clear states from your hardware. Most notably serial ports and tape drive software may not completely understand the state of the device left over from the other OS. (3) For some stupid reason the PC allocates partition slot 4, then 3, then 2, and then 1. Yep. They are backwards. Go figgure. 8-) Rob.
tmh@prosun.first.gmd.de (Thomas Hoberg) (05/07/91)
In article <1991Apr24.074220.17639@jet.uucp>, cm@jet.uucp (colin manning) writes: |> Ideally, there would not be all these seemingly unnecessary restrictions |> concerning support for different partition types, sizes etc. In my opinion, |> whoever designed the fdisk partition table structure left a lot to be |> desired - why only allow at most 4 partitions on a drive ? and why restrict |> the cylinder numbers to 10 bits ? It seems to me that to have allowed a |> reasonable number of partitions (say 32) and to use 32 bit disk addressing |> would not have been too hard. The cost would have been, say, an additional |> 256 bytes or so to save a lot of hassle. I thank God they included the partition table at all. Remember that the partition table first appeared on the IBM PC/XT with DOS 2.0. The XT had a 10MB hard disk and for operating systems there was DOS, DOS and DOS. CP/M-86 was dying and Xenix was "announced" (it never *really* materialzed for the 8088, just like the multi-tasking DOS 2.5) |> |> Also, why is it that support for DOS 4 partitions is non-existant in ISC and |> SCO ? DOS 4 seems to have been around for quite long enough for support to |> have been added. Most people could live with 32MB DOS partitions and many without any. |> |> Anyway, I'd be interested in information on any of the following. I'll |> post a summary in due course if there's sufficient interest. |> |> 1. Is it possible to have an easy way of selecting between booting DOS |> or Unix on an ISC system, without having to remember to use fdisk |> every time to change the active partition ? Ideally the source to |> a boot program that could be put on a primary DOS partition would |> be nice (like the one I use with SCO). I posted a partition booter some time ago, but BOOTMENU seems to have take over the market. |> 2. Although ISC and SCO do not seem to have any support for >32Mb DOS 4+ |> filesystems: |> i. When is support for these expected from ISC and SCO ? Perhaps never, but while they are at it, why not add High Sierra, HPFS, Mac-FS, VMS, 370, Cyber, creeping featureism and melancholia. |> ii. When you use SCO, and you interrupt the auto-boot to boot DOS (by |> typing 'dos' at the : prompt), will it boot correctly off a >32Mb |> DOS 4 partition ? I hope so. |> iii. If you try to have >32Mb DOS 4 partitions on a SCO or ISC system, |> does the Unix safely ignore them even though they cant use them ? |> Yes |> 3. Is it possible to have both SCO and ISC Unix on the same machine, in |> different partitions, and have some way of selecting between the 2 |> at boot time ? ISC (and DOS 5) depend on their partitions to be active to boot. I don't know about SCO. If your partition booter rewrites the partition table it should work. |> |> 4. Does ISC recognise SCO partitions and vice-versa ? Both recognize Xenix file systems. ISC FFS and SCO 1k file system might use different magic numbers. |> |> Many thanks in advance, |> |> -- |> - Colin Manning, cm%jet.uucp@ukc.ac.uk (world) OR cm@jet.uucp (UK only) |> - Disclaimer: Please note that the above is a personal view and should not |> be construed as an official comment from the JET project. -- tom ---- Thomas M. Hoberg | UUCP: tmh@bigfoot.first.gmd.de or tmh%gmdtub@tub.UUCP c/o GMD Berlin | ...!unido!tub!gmdtub!tmh (Europe) or D-1000 Berlin 12 | ...!unido!tub!tmh Hardenbergplatz 2 | ...!pyramid!tub!tmh (World) Germany | BITNET: tmh%DB0TUI6.BITNET@DB0TUI11 or +49-30-254 99 160 | tmh@tub.BITNET