What is the most important limitation (problem) of FAT16 and FAT32?

Question

This question pertains to operating systems. Also can you make it clear which one is FAT16 and which one is FAT32.

Answer 1

DOS and Windows 3.x use the FAT16 (File Allocation Table) file system. Windows 95 OSR2 and Windows 98 can use Microsoft's new FAT32 file system. FAT32 allows hard drive partition sizes greater than 2-GB. It also makes more efficient use of hard drive space than does FAT16 on partitions larger than 512-MB.
Table 1 below shows the minimum cluster sizes for different partition sizes for both FAT16 and FAT32 formats. The wasted space entries are estimates. The actual space waste realized on a particular system depends on the actual mix of file types and sizes specific to the hard drive.

Where hard drive partition sizes range from 512-MB to 4095-MB the FAT32 system can provide a 21% to 46% reduction in estimated space waste. FAT file system comparisons are not applicable for partition sizes less than 512-MB because smaller partitions cannot be formatted to the FAT32 system.

Windows 98 includes a utility to convert FAT16 partitions to FAT32 partitions. However, the Windows 98 utility is a one-way process. You will not be able to convert the FAT32 partitions back to FAT16 partitions. However, Partition Magic version 3.x can convert FAT32 to FAT16 and FAT16 to FAT32 partitions.

Once you convert your partition to FAT32, the only operating systems that will be able to read and to write to your FAT32 partitions are Windows 95 OSR2 and Windows 98.

Answer 2

FAT16: The FAT used for most older systems, and for small partitions on modern systems, uses a 16-bit binary number to hold cluster numbers. When you see someone refer to a "FAT" volume generically, they are usually referring to FAT16, because it is the de facto standard for hard disks, even with FAT32 now more popular than FAT16. A volume using FAT16 can hold a maximum of 65,526 clusters, which is 2^16 less a few values (again for reserved values in the FAT). FAT16 is used for hard disk volumes ranging in size from 16 MB to 2,048 MB. VFAT is a variant of FAT16.

FAT32: The newest FAT type, FAT32 is supported by newer versions of Windows, including Windows 95's OEM SR2 release, as well as Windows 98, Windows ME and Windows 2000. FAT32 uses a 28-bit binary cluster number--not 32, because 4 of the 32 bits are "reserved". 28 bits is still enough to permit ridiculously huge volumes--FAT32 can theoretically handle volumes with over 268 million clusters, and will support (theoretically) drives up to 2 TB in size. However to do this the size of the FAT grows very large; see here for details on FAT32's limitations.

Answer 3

Well, arguably the most important limiting factor of those file systems is how much space each of them is able to deal with, and how well it does so - since file systems are all about data and handling it.

I believe a fat16 format is limited to being able to manage/store 2GB worth of data - so even if your drive is larger than that, that is all you will be able to work with. Fat32 on the other hand, is able to work with up to 2 terabytes of data (thats over 2000 gigabytes, 2048 in fact)

fat32 handles data more efficiently as well. You could probably google the two and come up with the technical details of that, as it exceeds my knowledge, thereby reducing me to copy/paste something you could get more in depth elsewhere

So which is which - well, fat32 is the better and more current of the two. fat16 was back in early windows days (like 95 and sooner, tho i think 95 eventually got adjusted to be able to handle fat32).

Answer 4

The FAT16 can access only 2^16 clusters as FAT32 can access 2^32 clusters (in theory, 2^28 in fact). A cluster is the smallest unit assignable on a hard drive. It is composed of sectors.

At the begining the hard drives have small capacities (some Mb). The FAT16 was designed for hard drives up to 2 Gb, but in that case, the size of a cluster is 32,768 bytes = 64 sectors of 512 bytes. That means, if you have a small file (less than 32,768 Bytes or 32Kb) it is written on one cluster.....even if the file is only some bytes. You loose a lot of space. Another example is if your file is 32,769 bytes...2 clusters are needed to write your file. You reserve 65,536 bytes (64Kb) on you hard drive to write only 32,769 bytes = 32Kb + 1 byte....what a waste of space.

I let you imagine what is the loss of space in the case you have a bunch of file of less than 512 bytes.....that means you have to reserve 32 Kb of space for only 512 bytes....You use only 1/64th of your drive space due to a cluster too big.

The solution was to be able to access more clusters. So, the FAT32 appears which can access this time 2^32 clusters (2^28 in fact).
That means, on the same 2 Gb hard drive, now you can assign every single sector to a cluster. You don't waste anymore your free space on the hard drive !

In general a cluster is composed of 8 sectors of 512 bytes = 4,096 bytes = 4 Kb. You can change that parameter when you format your drive (only in FAT mode).

Answer 5

FAT16 is 2GB max, 2^16 sectors max meaning variable chunk size.

FAT32 lifts those limitations to par with NTFS, Ext2 and the likes.