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Number : 7918 Date : 2004-05-19 Author : Kan Yabumoto Subject : Re: Using /CLONE to restore the bootdrive in FAT16 ? Size(KB) : 4
Garry wrote: > I might be wrong but I don't think you can FDISK > a HDD without creating a primary partition. I believe you can create an extended partition without a primary partition. > However this isn't a problem as far as your drive assignments > go as you can re-assign the drive letters in windows > to be whatever you want. This is not true in any of Win9X/ME systems. The ability to assign a drive letter to a disk by the user is only with the NT-family Windows (which is done through entries in the system registry). It is my understanding that Win9X/ME simply takes over the file system from the underlying DOS (which initiates the disk I/O operation before it enters the Windows environment) which in turn relies its drive-letter assignment on what the BIOS detects at the beginning. The only exception to this rule is via the installable file system (e.g., MSCDEX.EXE, DATMAN.EXE, etc. which usually mimic the network drive creation like NET.EXE). There are other techniques that allows a program to inject a new drive letter by emulating a hard disk in which cases, the driveletter- assignment must follow the usual BIOS rule. There might be other non-Microsoft techniques to manipulate driveletters which is outside the scope of my discussion here. The BIOS driveletter assignment scheme goes like this: When you boot a system into the DOS, the drive letter assignment was done by first-come-first-served basis C: first disk, first primary partition D: second disk, first primary partition E: third disk, first primary partition ... Note the first "round" of drive letter assignment is always done on the one-disk-one-driveletter scheme. Then, 1st disk is revisited and if it contains the extended partitions with proper format (FAT), such volumes will be assigned driveletter. In this example F:, G:, and H: are on the 1st disk. F: first disk, 1st partition in the extended partition G: first disk, 2nd partition in the extended partition H: 2nd disk 1st partition in the extended partition This scheme is not only confusing, but quite dangerous. For example, when the second disk fails to be initialized properly at the beginning of a boot sequence, DOS will usually timeout in its repeated attempts to initialize and start assigning the next available drive letter to the next one in the ranking. All the rest of the drive letters will be "shifted". That is, when 2nd disk fails to be initialized at the boot time, the disk's presence will be ignored for all practical purposes. This is one of the prominent scenarios that motivated us to invent the /ILS and /ILD features in XXCOPY. > You will need to FDISK, make active and format the new > replacement HDD to make it bootable (see Tech Bulletin #10 > for the details). FDISK is a very frustrating tool. Since it refuses to make a partition "active" only when the disk is attached to the system as the first disk (DISK1 in FDISK's way of assigning ---- usually called DISK0 in NT/2K/XP), you may keep a diskette with FDISK handy and run FDISK after hooking up the disk as the first disk on the system (usually the IDE Primary Master channel). As Garry said, XXTB #10 explains this aspect but make sure that you understand that FDISK can make only the 1st disk's primary partition "active". BTW, making a partition "active" is a very simple operation. All it takes is to set the flag byte (the 1st of the 16-byte partition table entry) to 80h. There is no technical reason why FDISK should not allow the user to set active partition on any disk. It's one of stubborn things that Microsoft never changed. I'm not sure if what Garry said was doable. > After that, you need to transfer the OS from your backup > drive to the new C:. Since you'll be operating in true DOS, > you won't have long filename support. Although you could > do the recovery with a bit of fiddling around, I think > you'd be better off doing the following: > > 1. Make your backup drive a bootable clone using the > steps in Tech Bulletin #10 except that it would not > be set as active. > > 2. Re-assign the drive letters in windows to the > configuration you want. Step 2 is a problem in the suggested sequence. I don't believe you can assign a drive letter at will in DOS/Win9X. Kan Yabumoto
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