ch12 - Chapter 12: Mass-Storage Systems Chapter 12:...

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Unformatted text preview: Chapter 12: Mass-Storage Systems Chapter 12: Mass-Storage Systems 12.2 Silberschatz, Galvin and Gagne 2005 Operating System Concepts Chapter 12: Mass-Storage Systems Chapter 12: Mass-Storage Systems Overview of Mass Storage Structure Disk Structure Disk Attachment Disk Scheduling Disk Management Swap-Space Management RAID Structure Disk Attachment Stable-Storage Implementation Tertiary Storage Devices Operating System Issues Performance Issues 12.3 Silberschatz, Galvin and Gagne 2005 Operating System Concepts Objectives Objectives Describe the physical structure of secondary and tertiary storage devices and the resulting effects on the uses of the devices Explain the performance characteristics of mass-storage devices Discuss operating-system services provided for mass storage, including RAID and HSM 12.4 Silberschatz, Galvin and Gagne 2005 Operating System Concepts Overview of Mass Storage Structure Overview of Mass Storage Structure Magnetic disks provide bulk of secondary storage of modern computers Drives rotate at 60 to 200 times per second Transfer rate is rate at which data flow between drive and computer Positioning time ( random-access time ) is time to move disk arm to desired cylinder ( seek time ) and time for desired sector to rotate under the disk head ( rotational latency ) Head crash results from disk head making contact with the disk surface Thats bad Disks can be removable Drive attached to computer via I/O bus Busses vary, including EIDE, ATA, SATA, USB, Fibre Channel, SCSI Host controller in computer uses bus to talk to disk controller built into drive or storage array 12.5 Silberschatz, Galvin and Gagne 2005 Operating System Concepts Moving-head Disk Machanism Moving-head Disk Machanism 12.6 Silberschatz, Galvin and Gagne 2005 Operating System Concepts Overview of Mass Storage Structure (Cont.) Overview of Mass Storage Structure (Cont.) Magnetic tape Was early secondary-storage medium Relatively permanent and holds large quantities of data Access time slow Random access ~1000 times slower than disk Mainly used for backup, storage of infrequently-used data, transfer medium between systems Kept in spool and wound or rewound past read-write head Once data under head, transfer rates comparable to disk 20-200GB typical storage Common technologies are 4mm, 8mm, 19mm, LTO-2 and SDLT 12.7 Silberschatz, Galvin and Gagne 2005 Operating System Concepts Disk Structure Disk Structure Disk drives are addressed as large 1-dimensional arrays of logical blocks , where the logical block is the smallest unit of transfer....
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This note was uploaded on 01/21/2012 for the course COMPUTER CSCI 593 taught by Professor Hamnes during the Spring '11 term at Aston University.

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ch12 - Chapter 12: Mass-Storage Systems Chapter 12:...

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