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View Full Version : MS-DOS partition conundrum. (supporting legacy systems is PITA)



drbob
12-14-2011, 07:40 PM
The problem:

On a new disk, I create 2 logical partitions (one 1GB, one 100MB) in ms-dos 6.22 with fdisk - works fine from within dos but the 1GB partiton will not mount in windows 7. If I create the partitions within windows they mount fine in windows but are not visible in DOS. fdisk can see the extended partition but not the logical partitions within it.

I've managed to work around the issue by creating 3 primary partitions but would love to know if anyone here knows why/what may have caused this issue. In the dim mists of my memory I seem to remember reading an article that mentioned the dos fdisk being quirky but my google fu hasn't thrown up any examples of this exact issue.

Background:

A close family member has been nursing a DOS app that is key to his business since the maker stopped supporting it (amazingly this was only in 2007).

I've been going in regularly and taking disk image back-ups from the ancient 486 server as I did not trust the zip disk based backup solution provided by the manufacturer (restore instructions - call us to talk you through it at $$$ per incident)

Yes, I've been trying to convince him to upgrade but the sofware company wants a lot of money (think 5 figures) to license the shiny windows version and for migration from DOS to a modern system. The old software still currently meets his modest needs.

Recently the 1.2GB WD caviar drive in the server started to fail so I was tasked with replacing it (with an 80GB WD caviar blue, clipped via jumper settings to 2GB) which led to the partitioning problems described above.

I've tried creating the partitions manually in windows using Paragon Partiton Manager, I've also seen the problem when restoring the disk image using Macrium reflect (annoyingly it doesn't seem to do a true full disk image, I think it recreates the partitions using windows calls before restoring into them rather than a true sector by sector restore of the entire disk including partition table)

tronnc
12-14-2011, 07:45 PM
Couldn't you just emulate the DOS system completely with a virtual machine?

mkozlows
12-14-2011, 07:51 PM
Or use DOSBOX?

drbob
12-14-2011, 07:54 PM
Couldn't you just emulate the DOS system completely with a virtual machine?

Still testing that route, it's a networked system (one slave PC and the server) and whilst it initially appeared to work ok under MS virtual PC 2007 over extended use I get disk errors when opening files over the network. I suspect an incompatibility between dosidle and the network software, invisible lan (http://www.invisiblesoft.com/invlan/index.shtml). Also bless the people at Invisible Software for keepin their support pages up - without them I would not have been able to get it working in a VM at all.

drbob
12-14-2011, 07:58 PM
Or use DOSBOX?

DOSbox is mainly for games and unfortunately this business software won't even load within it.

Omniscia
12-14-2011, 08:59 PM
Man, I think my mechanic still runs a DOS application to manage his parts inventory.

chequers
12-14-2011, 09:48 PM
You should fight to get it working in a VM. Dealing with progressive failure of ancient hardware is a nightmare.

Anyway, this sounds like a filesystem incompatibility. Did you format the partition you created in WIn7 as FAT16?

XPav
12-14-2011, 09:48 PM
Have you tried using a more capable partitioning tool like one off a Linux rescue disk to examine/create the partitions?

Brandon Clements
12-15-2011, 07:35 AM
HOLY OLD SHIT BATMAN.

Ok, now that's out of the way, try gparted off most any Linux live cd. It'll work better than fdisk; dunno if it'll actually solve the problem you're having though.

rei
12-15-2011, 10:26 AM
I got nothin'.



DEVICE=C:\Windows\HIMEM.SYS
DOS=HIGH,UMB
DEVICE=C:\Windows\EMM386.EXE NOEMS

Talisker
12-15-2011, 10:27 AM
Try vmware player 4. It's free.

Dawn Falcon
12-15-2011, 10:34 AM
I got nothin'.

Pfft, try making a non-extended keyboard driver load to free up JUST enough memory to run a game.

...

On second thoughts, I SO don't miss those days.



Anyway, to the op, I'd try running it with FreeDOS and seeing if that works, it's a lot more network-aware.
http://www.freedos.org/


(I'd also second GParted for partitioning)

drbob
12-15-2011, 06:26 PM
Anyway, this sounds like a filesystem incompatibility. Did you format the partition you created in WIn7 as FAT16?

Yep, FAT16 was used in Win 7.

The only thing that occurs to me as the possible cause is that the DOS system recognised the HD as a 2GB drive whereas the Win 7 saw it as a 32GB drive. I was careful to ensure the partions I created were within the first 2GB for this reason but maybe I missed somthing. Still doesn't explain why the 1GB logical partition created by fdisk could not be mounted in windows.

Anyways, thanks for the tips guys. I've already fought with other VMs (virtualbox, vmware) and apart from Virtual PC, none of them have decent enough DOS support. For most VMs the advice seems to be not to run a DOS memory manager - which is not useful advice for this app as if I don't load some of the network drivers high there isn't enough free memory to load the server.

I'll take a look at switching to freedos. I already use cutemouse from freedos in my current VM setup, I tried JEMM too but that caused random crashes whilst everything is stable with EMM386 apart from the network disk read errors. Maybe I'll have more luck if I switch completely to freedos, though reading the wiki I see nothing about it being more network aware, the networking page seems to talk about all the same old 3rd party apps you need to get a network running in MS-DOS.