- Reformatting will not delete your personal data when it placed on a different partition than the operating system
- Temporary files will not cause file fragmentation, when it is placed on a separate partition.
- Dual booting operating systems will not interfere with each other, when each operating system is placed on separate primary partitions
- Enables organization of your data on a level beyond directories.
- The outer edge of the HDD has the best performance, by creating a partition here, then it is possible to manually decide what files should have the best file-performance. (Defragmentation tools solves this automatically)
- Faster access to files and directories, when using FAT16/32 on large partition the File Allocation Table(FAT) will become extremely large and slow to search through (NTFS can solve this, though one should only use 85% of the partition)
- Less slack with small files, when using FAT16/32 the cluster-size can become quite big, causing a small file to use a lot more space than its actual size (NTFS can solve this)
- Defragmentation is not required for the entire HDD, when having several partition only have to defragment the partition where files are often create/deleted
- Gives a little more security, incase the File Allocation Table (FAT/MFT) on one partition is corrupted, then it will not affect the other partitions. (Backup solves this)
- File copy/move between partitions on the same HDD is extremely slow
- One can still organize data by using folders.
- Partitions are less dynamic than folders, thus one can reach the partition limit even though there is still plenty of space on the HDD. (Though one can use Partition Magic to resize the partition)
- The HDD is forced to make a long seek when accessing a file on another partition
More Info Bob Watson - FDISK Tutorial
More Info FDISK Simulation
More Info MS KB255867