tailieunhanh - Bài giảng Hệ điều hành nâng cao - Chapter 12: Mass - Storage Systems

Bài giảng Hệ điều hành nâng cao - Chapter 12: Mass - Storage Systems trình bày tổng quan về cấu trúc Mass Storage, cấu trúc đĩa, quản lý lưu trữ, trao đổi và thiết bị lưu trữ,.Đây là tài liệu tham khảo thuộc chuyên ngành Công nghệ thông tin. | Chapter 12: Mass-Storage Systems 1 Chapter 12: Mass-Storage Systems Overview of Mass Storage Structure Disk Structure Disk Attachment Disk Scheduling Disk Management Swap-Space Management RAID Structure Stable-Storage Implementation Tertiary Storage Devices 2 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 3 Overview of Mass Storage Structure Magnetic disks provide bulk of secondary storage of modern computers Drives rotate at 60 to 250 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 That’s bad Disks can be removable Drive attached to computer via I/O bus Busses vary, including EIDE, ATA, SATA, USB, Fibre Channel, SCSI, SAS, Firewire Host controller in computer uses bus to talk to disk controller built into drive or storage array 4 Magnetic Disks Platters range from .85” to 14” (historically) Commonly ”, ”, and ” Range from 30GB to 3TB per drive Performance Transfer Rate – theoretical – 6 Gb/sec Effective Transfer Rate – real – 1Gb/sec Seek time from 3ms to 12ms – 9ms common for desktop drives Average seek time measured or calculated based on 1/3 of tracks Latency based on spindle speed 1/(RPM * 60) Average latency = ½ latency (From Wikipedia) Magnetic Disk Performance Access Latency = Average access time = average seek time + average latency For fastest disk 3ms + 2ms = 5ms For slow disk 9ms + = Average I/O time = average access time + (amount to transfer / transfer rate) + controller overhead For example to transfer a 4KB block | Chapter 12: Mass-Storage Systems 1 Chapter 12: Mass-Storage Systems Overview of Mass Storage Structure Disk Structure Disk Attachment Disk Scheduling Disk Management Swap-Space Management RAID Structure Stable-Storage Implementation Tertiary Storage Devices 2 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 3 Overview of Mass Storage Structure Magnetic disks provide bulk of secondary storage of modern computers Drives rotate at 60 to 250 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 .

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