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the SCSI-2 (also known as fast Fast SCSI ) specification.
SCSI-2 is an extensive enhancement of the very limited original SCSI
Important goals of this evolution of the SCSI standard were to improve performance, enhance reliability, and add features to the interface. However, the most important objective was to formalize and properly standardize SCSI commands.
SCSI-3 (also known as Ultra SCSI ) began in 1993. It has grown to be a set of standards rather than a single standard. It supports both parallel and serial data transmission, supports FireWire connections and increases the possible rate of data transfer to 320 MBps and higher.
The most implemented form of SCSI, is the SCSI-3 Parallel Interface (SPI )
The latest revision of SPI will be called the SCSI-3 Parallel Interface 4 or SPI-4 . It is still in development. The one feature that we now know will be included in SPI-4 is yet another doubling of maximum throughput on the SCSI bus. It is expected to soon be rated at 640 MBps to 1280 MBps.
Termination prevents an echo effect from the electrical noise and reflected data at the end of the SCSI daisy chain, which can cause interference with data transmission. Each end of a SCSI chain must be terminated.
The most common implementations have a serious drawback in that when files are deleted and new files written to the media, their fragments tend to become scattered over the entire media, making reading and writing a slow process.
A disk is divided into partitions. Under the FAT file system each partition is divided into clusters, each of which can be one or more sectors, depending on the size of the partition. Each cluster is either allocated to a file or directory or it is free (unused). A directory lists the name, size, modification time and starting cluster of each file or subdirectory it contains.
At the start of the partition is a table (the FAT) with one entry for each cluster. Each entry gives the number of the next cluster in the same file or a special value for “not allocated” or a special value for “this is the last cluster in the chain”.
FAT32 is a derivative of the FAT file system that supports drives over 2GB. FAT32 drives can contain more than 65,526 clusters, smaller clusters are used than on large FAT16 drives, resulting in more efficient allocation of space on the drive.
The 32-bit FAT includes four bytes per cluster within the File Allocation Table. This differs from FAT16 and FAT12 in that those files systems contain 2 bytes and 1.5 bytes within the File Allocation Table, respectively.
Formatting a volume with the NTFS file system results in the creation of several System Files and the Master File Table (MFT) , which contains information about all the files and folders on the NTFS volume.
The first information on an NTFS volume is the Partition Boot Sector . Figure below illustrates the layout of an NTF volume when formatting has finished.