The contents of this chapter include all of the following: Discuss the principal requirements for memory management, understand the reason for memory partitioning and explain the various techniques that are used, understand and explain the concept of paging,. | CSC 322 Operating Systems Concepts Lecture - 26: by Ahmed Mumtaz Mustehsan Special Thanks To: Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. (Chapter-5) Silberschatz, Galvin and Gagne 2002, Operating System Concepts, Ahmed Mumtaz Mustehsan, GM-IT, CIIT, Islamabad 1 Chapter 5 Input/ Output Hardware Disk (Magnetic / Optical ) Lecture-24 2 Ahmed Mumtaz Mustehsan, GM-IT, CIIT, Islamabad Disks Called Magnetic (hard) disk Reads and writes are equally fast Good for storing file systems Disk arrays are used for reliable storage (RAID) Optical disks (CD-ROM, CD-Recordable, DVD) used for program distribution Seek time is 7x better, transfer rate is 1300 x better, capacity is 50,000 x better. Floppy vs hard disk (20 years apart) Disks-more stuff Some disks have microcontrollers which do bad block re-mapping, track caching Some disk controllers are capable of doing more then one seek at a time, . they can read on one disk while writing on another Real disk geometry is . | CSC 322 Operating Systems Concepts Lecture - 26: by Ahmed Mumtaz Mustehsan Special Thanks To: Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. (Chapter-5) Silberschatz, Galvin and Gagne 2002, Operating System Concepts, Ahmed Mumtaz Mustehsan, GM-IT, CIIT, Islamabad 1 Chapter 5 Input/ Output Hardware Disk (Magnetic / Optical ) Lecture-24 2 Ahmed Mumtaz Mustehsan, GM-IT, CIIT, Islamabad Disks Called Magnetic (hard) disk Reads and writes are equally fast Good for storing file systems Disk arrays are used for reliable storage (RAID) Optical disks (CD-ROM, CD-Recordable, DVD) used for program distribution Seek time is 7x better, transfer rate is 1300 x better, capacity is 50,000 x better. Floppy vs hard disk (20 years apart) Disks-more stuff Some disks have microcontrollers which do bad block re-mapping, track caching Some disk controllers are capable of doing more then one seek at a time, . they can read on one disk while writing on another Real disk geometry is different from geometry used by driver, since controller has to re-map request for (cylinder, head, sector) onto actual disk Disks are divided into zones, with fewer sector at the inner side, gradually progressing to more on the outer side (a) Physical geometry of a disk with two zones. (b) A possible virtual geometry for this disk. Disk Zones Redundant Array of Inexpensive Disks (RAID) Parallel I/O to improve performance and reliability vs SLED, Single Large Expensive Disk RAID; A bunch of disks which appear like a single disk to the OS SCSI disks often used-cheap, 7 disks per controller SCSI is set of standards to connect CPU to peripherals Different architectures-level 0 through level 6 RAID Redundant Array of Independent Disks Consists of seven levels, zero through six Integrated Performance Redundancy With the use of multiple disks, there is a wide variety of ways in which the data can be organized and in which redundancy can be added to improve reliability. This could make it .
