Oh. this happened to me too. What has actually happened is this.
- You have a single hard disk or maybe two.
- You already have another OS installed.
- The other OS has your logical partitions (or maybe the complete hard disk)in such a format which anaconda (the white fedora installer) does recognize but doesn't give a name to (for e.g. FAT32, NTFS etc.) Fedora will only name partition types like ext, brtfs etc.
So far I'm assuming you have Windows installed. (Same here)
Now anaconda will assume that your complete hard disk is used up. The 2 MB shown is used to identify your hard disk (IDE identifiers). But Windows shows that you have 100 GB free. Now problem is this space is not considered unallocated. It is considered as fixed for use by Windows. Remember Windows only hides data when you delete it.(waiting to be overwritten) But anaconda needs either formatted partitions or unallocated space.
Hence the error message.
I think the possible solutions are:
1. You shrink the current system by the amount you want or let anaconda do it automatically. This will probably leave you some unallocated space.
2. You let Fedora do reclaiming of space. (You might lose data!)
3. You manually edit partitions (Advanced users only!) using Gparted etc.
Since I'm a novice too, I think you should wait for more replies.
Did you delete files, or did you resize partitions? To install another operating system, you need unallocated space, not just used space.