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The Windows NT/2000 operating systems and,
most recently, the Windows XP operating system have some obvious and
not so obvious differences. Many of the differences these operating
systems have as opposed to the 9x environments are unseen. However,
they are very important concepts to understand in order to fully grasp
the different environments in which these operating systems are used.
For example, it must be considered whether the operating system will
be used for office or home and whether the computer will be part of a
network. Security issues must be taken into account, as well as the
types of programs that will be running on the operating system. All of
these factors will determine whether or not to choose the 9x or the
Windows NT, 2000, or XP operating system. Some of the biggest
differences to become familiar with when considering the contrasts
between these operating systems are the Windows NT File System (NTFS)
and File Allocation Table (FAT) file systems.
The main purpose of the file system is to store and retrieve data from the computer hard disk. How the data is organized, optimized, and retrieved comes from the file system on the hard drive. Hard drives store information on platters, which are metal and coated with a magnetic substance. How exactly is the data organized on those little platters? It is done with the file system. DOS/Windows is the most widely used operating system in the United States and many other parts of the world. Its file system is basically the standard from which other operating systems can read. Original FAT File System FAT16 File System The FAT file system is simple and reliable. If the computer happens to crash (if it stalls or will not respond) in the middle of an update, it will not lose any data. Without using a lot of memory, the FAT file system does many administrative Input/Output (I/O) tasks to areas of the partition. This ability gives the FAT file system a true advantage. Unfortunately, as a result of this capability, a file can become fragmented into small pieces, thus reducing performance. However, the FAT file system includes optimization tools to prevent this from occurring. FAT File System Utilities If the CHKDSK or SCANDISK utility does happen to find unallocated sectors on the disk, the user will be prompted whether or not these sectors should be changed into files. If the user was not in the middle of creating a new file when the computer crashed and then ran this utility, simply selecting "no" will cause the unallocated space to be be recycled as free space. However, if the user was in the middle of creating a new file when the system crashed, and the data that was lost is extremely valuable, "yes" should be selected. Then the recovered file scraps can be scanned for lost information. Sectors and Clusters Files are stored in clusters. Under this system, the hard
disk is divided into 512-byte pieces called sectors. The
sectors are then grouped into larger pieces called clusters.
Each cluster can hold only one file. The computer assigns these
clusters with a specific location to make it easy for the computer to
find them. The size of the clusters is determined by the size of the partitions
made on the hard disk. Figure
FAT32 File System With the FAT32 file system, data on the hard disk is able to be
stored in a much more efficient manner. With the previous FAT16
version, a 2 GB partition, with its cluster sizes of 32 KB, would end up
wasting a lot of otherwise useful space because only one file could be
stored in one particular cluster at a time. For example, with FAT16,
if there was a file that was only 1 KB, by using 32 KB clusters, the
other 31 KB of space would be wasted. Conversely the FAT32 file system
would allow a 4 KB cluster with a 2 GB partition, thereby reducing the
amount of wasted space. Figure
Added FAT32 Features In the FAT16 file system, the root directory can be located only at the beginning of the hard disk. This poses problems if this part of the hard disk becomes damaged. If this were to happen, the whole hard disk would become unusable. With the FAT32 file system, the root directory can be located anywhere on the hard disk. This is very useful because if the section of the hard disk containing the root directory were to become damaged now, the root directory could be moved to another section of the hard disk and the damaged portion of the hard disk could be repaired. Another benefit of FAT32 is its ability to use both the default and original copies of the File Allocation Table (FAT). Both FAT16 and FAT32 file systems maintain two copies of the FAT (the default and backup copy), but only FAT32 can use the backup copy as well as the default copy. This means that if a file allocation table becomes corrupted or fails, and the FAT32 file system is being used, the backup copy can be used until the default copy can be repaired. FAT16 can only use the default copy to run the operating system. This means that should the FAT become damaged or fail in some manner, the system will crash and become unusable. These added features of FAT32 not only make disk space usage more efficient and reliable but they will improve the overall performance of the operating system. Applications will respond at least 50 percent faster with FAT32 while using fewer system resources. NT File System (NTFS) The main concept behind the need to develop the NTFS file system
was that the FAT16 and FAT32 file systems were simply far too limited
in their capabilities to provide the advanced features that are
necessary when implementing an enterprise-level operating system. The
NTFS file system provides support for added features like file and
directory security by using Discretionary Access Control Lists (DACL) and
System Access Control Lists (SACL). DACL and SACL can perform operations on a file and monitor events that
will trigger the logging of actions performed on a file. In addition,
NTFS allows the administrator to set local permissions on files and
folders that specify which groups and users have access to them. This
includes setting the level of access that is permitted. NTFS file and
folder permissions apply both to users working at the computer where
the file is stored and to users accessing the file over the network
when the file is in a shared folder. With NTFS, share rights can also
be set that operate on shared folders in combination with file and
folder permissions. FAT only supports share rights. NTFS provides
added support to more efficiently recognize and address large hard
disks and volumes that exceed the size limitations that a FAT16 or
FAT32 file system could handle. In fact, the NTFS file system was
designed so that it will be able to map disks up to sizes that will
not even be seen in the next 20 years.
As stated earlier, NTFS was designed with the idea that the file system needs to be capable of managing global and enterprise level operating systems. Again, an area where the FAT file system fails is in its capability to recognize file names in any language besides English. This is because the FAT file system uses the ASCII 8-bit character set for its file and directory name scheme. NTFS employs the Unicode 16-bit character set for its name scheme, which allows NTFS users anywhere in the world to manage files using their native language (a 16-bit character set has greater ability to accommodate a native alphabet/language than would an 8-bit character set). This is an important feature, which provides for a global and enterprise level operating system. The Windows NT/2000/XP operating systems were designed to appeal to the corporate and business market. Features like security and being able to access large volumes of data are necessities to large corporations and businesses. NTFS has built-in transactional logging so that whenever a modification is about to take place to the file system, NTFS makes a note of the modification in a special log file. If the system crashes, NTFS can examine the log file and use it to restore the disk to a consistent state with minimal data loss. This feature is called Fault Tolerance. This is one more feature that the corporate and business community considers important. The loss of crucial data due to a computer crash could cost a lot of time and money. FAT has no provision for fault-tolerance. If a system crashes while creating or updating files and directories, the FAT on-disk structures can become corrupted. This situation can result in the loss of valuable data that is being modified, as well as a general corruption of the drive and the loss of much of the hard disk data. This risk is unnecessary and clearly unacceptable for the Windows NT/2000/XP target market. High Performance File System (HPFS)
The HPFS file system directory structure was the same as the FAT file system but allowed long file names of up to 254 characters. The FAT16 file system used the 8.3 naming system (eight characters followed by a three letter extension). Another aspect of HPFS was its ability to map hard disks up to 8 GB instead of 2 GB. Also, instead of clusters as the unit of management on the hard disk, HPFS used physical sectors. Overall system performance increased as a result of this file system but it lacked the necessary tools and security that NTFS would provide. Figure
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shows the cluster sizes with
the FAT16 file system, according to the size of the partition that was
chosen.
shows the cluster sizes available with the FAT32 file system,
according to the size of the partition chosen.
shows the utilization of disk space with different cluster sizes. This combined with the ability to recognize
partitions larger than 2 GB made the FAT32 file system an obvious
evolution of the DOS file system.
