Disk Partitioning - Disadvantages of Multiple Partitions

Disadvantages of Multiple Partitions

Creating more than one partition has the following disadvantages, as compared to having a single partition spanning the same disk area:

• Reduces the total space available for user storage on the disk, as it forces the operating system to duplicate certain file system administration areas on the disk for each partition.
• Reduces overall disk performance on systems where data is accessed regularly and in parallel on multiple partitions, because it forces the disk's read/write head to move back and forth on the disk to access data on each partition and to maintain and update file system administration areas on each partition. It also prevents disk optimizers from moving all frequently accessed files closer to each other on the disk, which could reduce the number and distance of required head movements. Files can still be moved closer to each other on each partition, but those areas themselves will still be far apart on the disk. (See "short stroking" considerations above.) This issue does not apply to Solid-state drives as access times on those are neither affected by nor dependent upon relative sector positions.
• Increases disk fragmentation because it lowers the average size of continuous free blocks on each partition - as compared to a single partition of the same overall size - after the same amount of data has been written to them.
• May prevent using the whole disk capacity, because it may break free capacities apart. For example, if you have a disk with two partitions, each with 3 GBs free (hence 6GBs in total), you can't copy a 4GB DVD image file on that disk, because none of the partitions will actually provide enough space for that - even though you have more than enough free capacity in total on the disk. If the same files on those two partitions would have been stored on a single partition spanning the whole disk, then the 4GB file could be easily stored in the 6GB of free space.
• Slows down moving data between different parts of the same physical disk. When moving data from one partition to other, the operating system actually has to copy the contents of the data file, even though it still remains on the same device in a single copy/instance. When using a single partition, moving data between directories will only require altering the file system administration areas, and the actual contents of the file will not be copied or moved inside the disk/device, thus resulting in a significantly faster completion of the operation.
• Hurts portability and might impose constraints on how entities might be linked together inside the file system. For example: the NTFS file system allows hard links to be created only as long as both the link and the referenced file reside inside the same volume/partition. Also under Windows if you're referencing a file on another partition, you can do that only by specifying the partition's assigned drive letter - which, however, might change with time and depending on the drives installed. This renders references invalid and dependent on actual drive letter assignment, which is not an issue if you have to reference files/directories only on the same partition, as in this case you can use directory-relative or root-relative references, without including the drive/partition letter.