FAT File Systems - Essay Example

? White Paper on FAT File Systems 4 August, File Allocation Tables (FAT) is of huge significance to the users of Compact Flash (CF) because the requirement of FAT type is different for the devices that are optimized with over 2.14 gigabytes (GB) of storage capacity unlike those that require only 2.13 GB. This topic has gained huge importance specifically after the hard disk’s application into the personal computers. This paper tends to create awareness among the camera users regarding the FAT through a comprehensive discussion of its history. Introduction: The subject of this white paper is the illustration of FAT File Systems. This white paper is directed at creating an understating among the users of camera regarding the File Allocation Tables, which are generally referred to as FAT. Because of the disparity between the need of FAT type among different devices, Compact Flash (CF) users need to be given a thorough understanding of the FAT so that they may be able to make the right choice as per their device. The scope of this white paper is limited to the discussion of history of FAT File Systems along with a brief review of the relation of FAT with the Compact Flash (CF) devices which generate files with sizes up to 5+ mega pixels. This white paper first gives a comprehensive account of the historical background of FAT. This is followed by a review of the use of FAT File Systems in CF. Finally, the findings are concluded in the last section. History of FAT File System: Development of FAT File System: In February, 1976, during his stay at the Albuquerque’s Hilton Hotel spanning five days, a child known as Bill Gates who has gained immense fame for his contributions in the world of computer developed and coded FAT (Gilbert). “FAT was designed for small disks and simple folder structures” (Microsoft). Replacement of floppy disks with double-sided diskettes: The original Personal Computers made use of floppy disks for carrying the data whose capacity usually used to be 180 kilobytes. After the floppy disks, use of double-sided diskettes increased. The double-sided diskettes used to be double the capacity of the floppy disks and were up to 5 ? inches in size. The initial DOS developers indicated the relation of sectors to individual files as well as identified the vacant tables by creating tables with a view to organizing the data. As a result of this, the Operating System (DOS) was able to use the limited space on the double-sided diskettes to the maximum limit. There was no more the need of availability of a continuous series of sectors for saving the files. It was possible to break up the data for the files and distribute that everywhere in the double-sided diskette in an increasingly organized and sequenced fashion; a process that is frequently referred to as fragmentation. Nevertheless, it was fortunate in those times to be able to keep the data in one diskette because one would not need to switch the diskettes in and out alternately time and again while the program’s operation would continue. Selection of table length: There are 768 sectors upon a diskette with a capacity of 360 KB. This required the table to be large enough in order to determine every single sector of the total of 768. There was also the requirement of some room for expansion because the developers were aware of the on-going creation of larger diskettes. Number of possible values permitted by the use of one byte per table did not exceed 512, so that would not practically serve the purpose. On the other hand, two bytes would waste the disk space by permitting 16384 entries. Thus, decision had to be made somewhere in between one and two bytes. So finally, table with the length of 12 bits that were equal to 1.5 bytes were chosen so that the usage of sectors on the first double-sided diskettes could be traced. As a result of this, 4096 possible values were permitted. Such a FAT table was able to deal with storage devices with the capacity as large as 2 GB provided that each entry referenced one sector of the capacity equal to 512 bytes. Cluster formation: This practice increased the length of tables so much that it became difficult to retrieve them. Also, these long tables were not possible to be stored in memory because the sizes of memory used to be less than 64 KB. This was why the idea of clusters was used. As a result, the minimum storage element increased from one sector to certain number of sectors on a device. This group of sectors was known as cluster. The size of cluster was 2 or 1024 bytes for the initial diskettes with the capacity of 180 KB. Thus, it would take 1024 bytes of a diskette for one to save a file of 500 bytes. Although it seemed a bit wasteful, yet the idea of cluster worked well for big-sized files. “The original DOS file system [FAT 16] … has fallen into disuse and been largely replaced by FAT 32” (Spotswood 2). Table 1.0 lays down the maximum clusters which the FAT can signify. Table 1.0: Number of clusters per fat (Heybruck). Replacement of FAT 16 with FAT 32: FAT 12 and FAT 16 have long been in use in the Compact Flash storage devices. However, FAT 16 became too small to deal with all sectors since the 4 GB Microdrive was introduced in the year 2003. Number of clusters that could be represented with 16 bits was no more than 65536. A single FAT could accommodate just 2.14 GB with 32 KB being the maximum size of cluster. Therefore, there was dire need to either make multiple partitions of the drive or else augment the size of FAT up to 32 bits. Inter-compatibility of FAT 16 and FAT 32: Operating systems using FAT 32 are also supportive for FAT 16. Therefore, a host that is compatible with FAT 32 will function just as good if it is operated with a FAT 16 storage device. However, care must be taken while re-formatting the FAT 16 storage device. There can be numerous results of using FAT 32 storage device in a host that is compatible with FAT 16. There is great likelihood of occurrence of the CF ERROR. It is hard to predict the result in different cases. Conclusion: For all the digital music players and cameras that experience a tough time dealing with numerous partitions, FAT 32 provides the ultimate solution with storage as large as 2.14 GB. Today, a large number of companies are using FAT 32 in their products. Interestingly, FAT 16 are still used in the 2 GB Microdrive because they offer compatibility with multiple devices despite the fact that they have been largely replaced with FAT 32 in most of the devices. Compact Flash devices that have exceeded the threshold of 2 GB of capacity have to make use of the FAT 32. Operating systems compatible with FAT 32 are quite supportive for FAT 16 devices while it can not be so said for the operating systems compatible with FAT 16. The information presented in this white paper is extremely useful for the camera users, particularly those who intend to buy a new digital music player or digital camera. It is customary for them to confirm that the product in the market does support FAT 32. This is compulsory for making it compatible with new and emerging CF storage devices that may surface in the market in the future. Works Cited: Gilbert, Howard. “FAT File System.” 1 Jan. 1996. Web. 4 Aug. 2011. . Heybruck, William F. “An Introduction to FAT 16/FAT 32 File Systems.” Hitachi Global Storage Technologies. 2011. Web. 4 Aug. 2011. . Microsoft. “FAT File System.” 2011. Web. 4 Aug. 2011. . Spotswood, Robert. “An Overview of File Systems v1.1.” pp. 1-6. n.d. Web. 4 Aug. 2011. . Read More