Chapter 8 – I/O

Publisher Summary This chapter presents various input/output (I/O) systems. As high performance systems get larger and faster, the needs for high performance I/O systems become more acute. Redundant array of inexpensive disks, systems (RAID), are collections of disk drives that are used for reliability and performance. There are five different RAID levels. The first RAID level consists of mirrored disks. At RAID level 2, there are sufficient check disks to be able to detect an error through the stored parity information and to be able to correct the error. The difference between the second and third RAID levels is that, at the third level, there is only one check disk per disk group. At the fourth RAID level, data units are kept in a single disk; instead of bit interleaving the data, it is section interleaved. At RAID level 5, the bottleneck at the single check disk per group is removed, and the check information is distributed among the other disks in the group.