Duke CPS 110 - File Systems and Disk Layout (24 pages)

Previewing pages 1, 2, 23, 24 of 24 page document View the full content.
View Full Document

File Systems and Disk Layout



Previewing pages 1, 2, 23, 24 of actual document.

View the full content.
View Full Document
View Full Document

File Systems and Disk Layout

67 views

Other


Pages:
24
School:
Duke University
Course:
Cps 110 - Introduction to Operating Systems

Unformatted text preview:

File Systems and Disk Layout I O The Big Picture Processor interrupts Cache Memory Bus I O Bridge I O Bus Main Memory Disk Controller Disk Disk Graphics Controller Graphics Network Interface Network Rotational Media Track Sector Arm Cylinder Head Platter Access time seek time rotational delay transfer time seek time 5 15 milliseconds to move the disk arm and settle on a cylinder rotational delay 8 milliseconds for full rotation at 7200 RPM average delay 4 ms transfer time 1 millisecond for an 8KB block at 8 MB s Bandwidth utilization is less than 50 for any noncontiguous access at a block grain Disks and Drivers Disk hardware and driver software provide basic facilities for nonvolatile secondary storage block devices 1 OS views the block devices as a collection of volumes A logical volume may be a partition of a single disk or a concatenation of multiple physical disks e g RAID 2 OS accesses each volume as an array of fixed size sectors Identify sector or block by unique volumeID sector ID Read write operations DMA data to from physical memory 3 Device interrupts OS on I O completion ISR wakes up process updates internal records etc Using Disk Storage Typical operating systems use disks in three different ways 1 System calls allow user programs to access a raw disk Unix special device file identifies volume directly Any process that can open the device file can read or write any specific sector in the disk volume 2 OS uses disk as backing storage for virtual memory OS manages volume transparently as an overflow area for VM contents that do not fit in physical memory 3 OS provides syscalls to create access files residing on disk OS file system modules virtualize physical disk storage as a collection of logical files Unix File Syscalls int fd file descriptor fd open bin sh O RDONLY 0 fd creat tmp zot 0777 unlink tmp zot char data bufsize bytes read fd data count bytes write fd data count lseek fd 50 SEEK SET mkdir tmp dir 0777 rmdir tmp dir bin etc tmp process file



View Full Document

Access the best Study Guides, Lecture Notes and Practice Exams

Loading Unlocking...
Login

Join to view File Systems and Disk Layout and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view File Systems and Disk Layout and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?