I saw a similar post from 2 weeks ago, but it doesn't not seem to match my situation, so here goes...

I'm trying to install RHEL 9 on a machine that already has WinXP. I have one 120 [GB] drive with the following paritition layout...
c: 37.25 GB NTFS - Primary partition
d: 37.25 GB NTFS - logical partition
g: 2 GB FAT 32 - Primary partition
and 38 GB of unallocated space.

My intent was to tell Anaconda to keep existing partitions and use free disk space, but I get the error message:

Partitioning failed: Could not allocate partitions as primary partitions.

Then I click OK again, and it gives me another error screen which says.

The following errors occured with your partitioning,
You have not defined a root partition (/),
Which is required for installation of Red Hat Linux to Continue.

I have < 4 partitions, so that's not the problem. I also have plenty of space. I don't know if I have the existing 3 paritions setup in some weird way (don't really understand the differences!).

Any help would be appreciated!

Your drive is probably partitioned as such
/dev/hda1 - c:
/dev/hda2 - extended partition
/dev/hda3 - g: primary
/dev/hda5 - d: logical

An extended partition in a nutshell is a container for logical partitions. It is the method that is used to create more then 4 partitions on a hard drive. IDs are as follows
1-4 are primary partitions
>=5 logical partitions.

I do not know about RHEL but the RH linux by default will create 3 partitions:
/
/boot
/swap

I would say that the extended partition is only as big as the logical drive so even though you have unallocated space you can only create one primary partition i.e. hda4. You need to resize the extended partition to include the 38GB of unallocated space. parted is a utility to resize partitions. If you boot the 1st install CD and select recovery mode. Then run parted. You can search the web for parted documentation.

Thanks for the response.

The only problem that [I think] I have with your suggestion is that the extended partition contains the logical drive d: (100% of the extended parition as you guessed), and I use D: for Windows data files (in case I have to reinstall WinXP - the O/S is on a separate partition). If I move the unallocated space to D:, I would still end up wiping D: altogether, correct?

Or, If I understand your suggestion, I will end up with a very large extended drive that can be split into the 3 logical drives that the install needs (/, /boot, /swap), correct? If I want to keep my data partition for windows, could I just split that very large extended drive into 4 logical partitions - 1 for Windows and 3 for Linux?

Could I also just take the unallocated space and make another extended partition, or is the catch that you can only have one extended partition per physical disk?