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First post, by konc

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Short version: How can one create aligned to the 1MB boundary logical drives in the extended partition, that are still 100% compatible with DOS FDISK? Is it even possible?

The full story: I wanted to experiment with OFORMAT mentioned in this thread but the setup I'm trying to achieve is a primary partition and a logical drive in the extended partition, pretty classic.

So I initially created the partitions using Win10 diskpart, but when I put the SSD back to the old PC, FDISK (of DOS 7.1) couldn't see any logical drive. I thought that the problem was because I created the partitions on a different machine, so I booted GParted directly on the old machine and did the same, with the same results. Photos show what FDISK should display vs what it displays when it doesn't recognize the logical drives, and the actual partitions as they appear in GParted

Now it was the first time I attempted something similar and a brief research, if my conclusions are correct, revealed that the EBRs modern tools create are perfectly fine for Win2000 and forward, but are not what DOS and Win98's FDISK expects (an aligned to 1MB boundaries primary partition is OK, the same for logical drives in the extended partition isn't).

So my question is how can one accomplish this? I imagine that some partitioning tool will be able to align and at the same time write DOS-compatible entries, but I thought to ask here first before I start blindly trying all the different programs.

Reply 1 of 3, by Stretch

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Please install the Windows 98 updates KB311561 and KB263044 from Microsoft and see if that resolves the issue.

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Reply 2 of 3, by konc

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I should have mentioned it, it's not the cosmetic bug of FDISK for large drives and the drive isn't larger than 64GB. It's the same even if you create 2 partitions of 1GB on a small CF and the trigger is a logical drive in the extended partition, but aligned/having a gap in front.

From what I understand it's not even a bug, modern tools for the Windows era than can align don't write an FDISK-compatible EBR.
Assuming my understanding is correct, I'm looking for a tool than can do both. If it's possible at all, because there is always the chance that the partition description structure FDISK expects cannot contain the information about alignment at all.

Reply 3 of 3, by weedeewee

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didn't see any mention of you trying this, so i'll just repeat the advice and the link to the first one suggesting it

Re: MS-DOS with aligned partitions on CF card, is it possible?

https://en.wikipedia.org/wiki/Ranish_Partition_Manager

Allows sector-precise editing of primary partitions, logical drives, and EBR extended partitions (type 05). A particularly rare feature of RPM is that it shows exactly where extended boot records are, advises the user of where they should be, and allows the user to put them anywhere.

RPM may show an error if the EBRs are not on the beginning of a head (relative to the beginning of the extended partition—type 0F). If partition alignments of this sort, are ignored, and the partition is edited by Windows XP disk manager, XP may delete the logical drives. This can happen if the extended partition is first edited by Windows Vista[5] or Windows 7.

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