Lecture3

Lecture3 - COT 5611 Operating Systems Design Principles...

Info iconThis preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon
Click to edit Master subtitle style 8/1/11 Lecture 6 COT 5611 Operating Systems Design Principles Spring 2010 Dan C. Marinescu Office: HEC 439 B Office hours: M-Wd 1:00-2:00 PM
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Lecture 6 8/1/11 22 2 Names and the three basic abstractions n ¨ write(name, value) ¨ file system: /dcm/classes/Fall09/Lectures/Lecture5.ppt n ¨ machine instructions ADD R1,R2 ¨ modules q Variables call sort(table) n ¨ HTTP protocol used by the Web and file systems Host: boticelli.cs.ucf.edu put /dcm/classes/Fall09/Lectures/Lecture5.ppt get /dcm/classes/Fall09/Lectures/Lecture5.ppt
Background image of page 2
Lecture 6 8/1/11 33 3 Memory n Hardware memory: ¨ Devices n RAM (Random Access Memory) chip n Flash memory 9 non-volatile memory that can be erased and reprogrammed n Magnetic tape n Magnetic Disk n CD and DVD ¨ Systems n RAID n File systems n DBMS (Data Base management Systems)
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Lecture 6 8/1/11 44 4 Attributes of the storage medium/system n Durability & the time it remembers n Stability ± whether or not the data is changed during the storage n Persistence “ property of data storage system, it keeps trying to preserve the data
Background image of page 4
Lecture 6 8/1/11 55 5 Critical properties of a storage medium/system n Read/Write Coherence 9 the result of a READ of a memory cell should be the same as the most recent WRITE to that cell. n Before-or-after atomicity & the result of every READ or WRITE is as if that READ or WRITE occurred either completely before or completely after any other READ or WRITE
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Lecture 6 8/1/11 66 6 time WRITE item A in cell M A M READ from cell M A M A A Read/Write Coherence l the result of a READ of a memory cell should be the same as the most recent WRITE to that cell. Before-or-after atomicity l the result of every READ or WRITE is as if that READ or WRITE occurred either completely before or completely after any other READ or WRITE Current READ/WRITE Previous READ/WRITE Next READ/WRITE
Background image of page 6
Lecture 6 8/1/11 77 7 Why it is hard to guarantee the critical properties? n Concurrency & multiple threads could READ/WRITE to the same cell n Remote storage & The delay to reach the physical storage may not guarantee FIFO operation n Optimizations & data may be buffered to increase I/O efficiency n Cell size may be different than data size & data may be written to multiple cells. n Replicated storage & difficult to maintain consistency.
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Lecture 6 8/1/11 88 8 Access type; access time n Sequential access ¨ Tapes ¨ CD/DVD n Random access devices ¨ Disk n Seek n Search time n Read/Write time ¨ RAM
Background image of page 8
8/1/11 99 Physical memory organization n RAM two dimensional array. To select a flip-flop provide the x and y coordinates.
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 10
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 45

Lecture3 - COT 5611 Operating Systems Design Principles...

This preview shows document pages 1 - 10. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online