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FDISK doesn't see SCSI hard drive's entire size

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First post, by Thallanor

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I have a quick question that has me a bit stumped.

I have an 8-bit ISA Trantor T128 SCSI controller and a Seagate ST157N-1 hard drive connected to it.

When I attempted to boot from this hard drive, I received a "Missing operating system" message. If I booted from floppy, I was able to see the hard drive. I decided to see if running FDISK /MBR and deleting all partitions and creating a new one might resolve the issue. It did! I was able to then format and use sys to transfer files over and could then restart the computer and boot from the Seagate.

The problem is that I noticed FDISK was only seeing the drive capacity as 18 MB, even though the hard drive is a 45 MB model. (I can confirm that when I was booting from floppy before using FDISK and navigating around the hard drive, it is indeed 45 MB in capacity.)

Does anyone know what might be causing FDISK to see the drive as anything other that its true capacity? I inserted the 5.25" NEC disk that came with the drive and using SCSITEST, it sees the controller as well as the hard drive, though the utility doesn't have the capability to show any more data beyond that. Is there a utility for SCSI controllers that might poll for more data, like the actual drive size? (Not that that would really resolve the issue, but it'd be nice to know that the SCSI controller sees it correctly, narrowing the problem down somewhat.) I also wonder if there might be a Trantor utility that would allow me to low-level format the drive and start completely from scratch? (I am going to Google for this a little bit, but if anyone knows, I'm all ears.)

I would like to install a larger SCSI hard drive in this computer at some point, so this is possibly a non-issue. If I had any other SCSI hard drives, I'd be curious to take a peek at what FDISK sees them as, but unfortunately, I only have this one right now.

Hopefully someone might be able to shed some light on this mystery. 😀

Reply 1 of 6, by retardware

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You seem to have DOS < 5.0.
Before DOS 5.0 there was a 32MB limit.
(Only exception was Compaq MS-DOS 3.31, which already supported 512MB)
So, upgrade to DOS 5+.
If the HDD size still isn't recognized correctly, try another host adapter.

Reply 2 of 6, by Jo22

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I think the same. The rarely used DOS 4.x also already supported 2GB though.. 😉
Same goes for more advanced DOSes of that time, such as PC-MOS and DR-DOS.
https://dos.fandom.com/wiki/MS-DOS_Version_History

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In what to one race is no time at all, another race can rise and fall..." - The Minstrel

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Reply 3 of 6, by Deksor

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Yeah the 32MB limitation is only for DOS3.3 and earlier. (That's why I've installed DOS 4.01 on my 286 😁). Actually that's probably the biggest feature this version of DOS brought. DOS 4.0 vs DOS 3.3 is kinda like DOS 7.1 vs DOS 7.0 except it might have more bugs (that should have been corrected in version 4.01)

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Reply 4 of 6, by Thallanor

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I'm using MS-DOS 6.22, both on the hard drive as well as the boot floppy that I used to fdisk, format, and sys the hard drive. 😒 I do not have a spare SCSI controller unless you count an old Mac, though that was the first Mac with SCSI and it's not 100% standards-compliant, so no idea what it might do, 🤣. 😀 But I can try that and see. I can't shake it though that it's still something a low-level format might fix, but I'll give that a whirl later today and see. I used to use SCSI daily as part of my role 15-20 years ago, but it's been so long now that I've forgotten a lot of this stuff. 😒

Thanks for the advice though - I wouldn't have thought of the MS-DOS version stuff either.

Reply 5 of 6, by retardware

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Then just use FreeDOS to set up and format the hard drive.
My AT has a 2005 73GB 15k Fujitsu drive hooked up at the ASC-19160, and DOS 7.1 also fails (format doing nothing).
So this behavior is common with newer stuff too.
But after FreeDOS partitioned + formatted, installing DOS 7 on the HD using SYS C: + xcopy, booting it from the HD works fine.

Reply 6 of 6, by Thallanor

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retardware wrote:
Then just use FreeDOS to set up and format the hard drive. My AT has a 2005 73GB 15k Fujitsu drive hooked up at the ASC-19160, a […]
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Then just use FreeDOS to set up and format the hard drive.
My AT has a 2005 73GB 15k Fujitsu drive hooked up at the ASC-19160, and DOS 7.1 also fails (format doing nothing).
So this behavior is common with newer stuff too.
But after FreeDOS partitioned + formatted, installing DOS 7 on the HD using SYS C: + xcopy, booting it from the HD works fine.

It's worth giving it a shot. I was trying a few different things today, but will gave that a shot tomorrow if i don't make much more progress. Thanks!

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