Re: [nukkad] compres - Blank Spaces

[Harshal Chhaya <>]

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VSRawat wrote:
> But in the disk storage system, it takes a minimum block size to store
> any file. Thus a FAT16 system would take 16 adjacent bytes (how come
> 2048?) whereas a FAT32 system would take 32 adjacent bytes (how come
> 4096?) to store any information.

The cluster size on a disk system is typically 2048, 4096 or 8192 bytes.
The File Allocation Table (FAT) provides a map of the clusters where
a file is stored. The operating system creates a FAT entry for 
each file that records where each cluster is located and their sequential 
order. 

The number after FAT (16 or 32) is the size in bits of each entry 
in the FAT. It does not refer to the cluster size.

If you assume that each FAT entry is only one digit long, it can refer
to at most 9 clusters (0-9) and the maximum disk size it can support
is 9 x the cluster size.

Thus a 16 *bit* FAT can refer to a maximum of 65335 clusters. Assuming
a cluster size of 2048 bytes, this means that a FAT16 system can
access a maximum disk of size 128 Mbytes (65335 x 2048). If you use 
larger clusters (say 8192 bytes), you can use a larger disk (512 Mbytes) 
with FAT16 but the downside is inefficient disk use. 

A FAT32 system supports much larger disks and is the standard for
Windows systems after Windows 95.


Mr. Ameer Ali also asked about changing the cluster size on a
disk. To the best of my knowledge, the cluster size of a disk
can be changed only by a low-level format. This means that you
would have to back-up all your files and applications, do a 
low-level format on your disk, and then re-install the operating
system, your applications and all your files. This is too much
work for very little, if any, gain. Note that using smaller clusters
means that a file will be stored across more clusters now and it
may take longer to access that file. It is usually best to stay 
with the current values when it comes to low-level items like
cluster size.

Regards,
Harshal



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