XOSL HOWTOs and FAQs v1.00
by Filip Komar (filip.komaremail.si)

III. Creating partitions

• But, how can you create 4 primary partitions with fdisk? - because, even when just one primary exists, fdisk says that "a primary partition already exists", and will not create any more.
• When you want to create one more primary partition with Partition Magic, it says than Windows 9x won't work if more than one primary partition exists.
• Windows won't boot from extended partitions so I started to create primary partitions and both Partition Magic and Ranish Partition Manager would not let me create more than 4. What should I do?
• How to create multiple primary partitions with any DOS or Windows boot floppy
• How DOS, Windows or OS/2 assign drive letters
• Preventing drive letter change when multibooting DOS, Windows or OS/2

III. Creating partitions

VERY IMPORTANT: Be careful on this issue: when you install other Operating Systems that use their own file system, you need to be careful of where a new file system may reside in an extended partition. Microsoft Operating Systems MS-DOS through Windows 98 or even Windows ME have a bug where, if the last logical partition in the extended partition is not a recognized file system type, and multiple visible FAT primary partitions exist, it will use the last logical partition as a FAT one in place of the next primary partition. But it will think the size of the partition is that of the primary partition. Data coruption can occur!

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But how can you create 4 primary partitions with fdisk? - because, even when just one primary exists, fdisk says that "a primary partition already exists", and will not create any more.

Most versions of DOS fdisk can't create more then one visible primary partition and one extended partition. If you hide a partition with XOSL, then it will appear under fdisk as a "non-DOS partition". If all the primaries are hidden then fdisk will be able to create what it thinks is the only primary. Of course, you must ensure that space is available for your proposed new partitions. Search documentation for detailed instructions.

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When you want to create one more primary partition with Partition Magic, it says than Windows 9x won't work if more than one primary partition exists.

If you'll hide all other primary partitions except the current one in XOSL you won't experience any trouble.

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Windows won't boot from extended partitions so I started to create primary partitions and both Partition Magic and Ranish Partition Manager would not let me create more than 4. What should I do?

The specification for the PC hard disk MBR sector allows maximum of 4 primary partitions. Each primary partition can contain an Operating System on its own (or just data), but can also be set up as an extended partition. An extended partition is a container for logical partitions, of which you can have any number. But some Operating Systems will only reference a limited number of partitions. Many Operating Systems such as Linux and BeOS, and many flavours of Unix, can boot from an extended or a logical partition. Windows can boot from a logical partition (this is not common knowledge) but this type of installation is a little tricky (for more information check this and also other documentation). It is also possible to have 2 or more Hard Drives, which would allow you to have 4 primary partitions per hard disk. That way you are able to boot 8 or more of your Operating Systems from primary partitions and as many others as you have logical partitions available for them. Don't forget hiding.

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How to create multiple primary partitions with any DOS or Windows boot floppy

This is required should you want to install more than one Operating System. Partitioning can be a destructive process for your data, and should be handled with care. Keeping to a regular Backup policy is highly recommended.

Make a boot floppy (at least it must also contain format.com, sys.com and fdisk.exe) and copy the XOSL installation files to another "XOSL Install" floppy.

Run fdisk and create the first primary partition. Be sure that you leave enough space for other Operating Systems and for data partitions. Reboot your system and format the new partition with the command "a:\format c: /s". Make sure that you format the right partition or else you'll lose data! Then install XOSL in that partition. Use the "DOS Drive" and not the "Dedicated Partition" installation. This way you'll be able to test it and get used to it. Later you should reinstall it to another partition (for more information read on). Reboot and create Boot item for floppy. You have to hide the first partition at this point.

Now put the boot floppy in and boot your new Boot item. Run fdisk again and create the second primary partition. Leave the non-DOS partition alone, because this is your hidden partition.

Again reboot and repeat format procedure. Remember to change the Boot item to also hide the new partition on reboot.

If you need a third primary partition then repeat the above once again.

After you have created any primary partitions you need (as above), you should create one more primary partition: extended. That partition is a "container" for logical partitions. You can create as many logical partitions as you like. Organize your data in logical partitions. My recommendation for XOSL is that it should be installed in a (hidden) logical partition, so create one more for that.

If you have more than one hard disk repeat the same procedure. Don't forget that each hard disk can contain up to 4 primary partitions. If you need more partitions than that, then create logical partitions.

Now is a good time for the reinstallation of XOSL to its previously prepared partition. Reboot and give yourself some time to create Boot items for all planed Operating Systems now. With each Boot item, hide all partitions except those for the current Operating System. If you need to share data between Operating Systems, make one or more logical partitions visible for that. Format shared data partitions to FAT16, because almost all Operating Systems can access that file system.

If an Operating System happens to overwrite XOSL, just restore XOSL with your "XOSL Install" floppy.

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How DOS, Windows or OS/2 assign drive letters

The boot partition always gets the drive letter "c:\" regardless of whether it is a primary or a logical partition. After that, drive letters are allocated sequentially to the first primary partition in each hard disk (hd2 primary as d:|, hd3 primary as e:\, hd4 primary as f:\, and so on). Then the logical partitions are assigned drive letters drive by drive, for example hd1 logicals 1-3 as g:\ h:\ I:/, hd2 logicals 1-2 as j:\ and k:\, and hd3 logical 1 as m:\. Finally are the rest of primary partitions in same order like logical partitions. Hidden partitions do not get a drive letter, and remember that multiple primaries are not visible in DOS/Windows/OS2 type Operating Systems, so only one primary per hd will have a drive letter.

Note: Windows NT or 2000 doesn't change assigned letters if partition is removed or hidden.

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Preventing drive letter change when multibooting DOS, Windows or OS/2

If you place partitions in the right order, you can avoid drive letter changes. If we look at different file systems, the most common one is FAT. So, create those partitions at the beginning of the hard disk. After them place FAT32 and finally any NTFS and HPFS partitions. Unix and Linux don't use drive letters, but there are other limitations depending on the Unix flavour in question.

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