[컴퓨터구조] 1129 (2)

Storage & I/O

Introduction

• I/O devices: input/output, storage
• I/O bus connections:

I/O bus connections

 

I/O System Characteristics

• Dependability
• Performance
  - Latency(= response time): desktop, embedded system에서 중요
  - Throughput(= bandwidth): server에서 중요

 

Dependability

Dependability

• Fault: failure of a component.

 

Dependability Measures

• Reliability: MTTF(mean time to failure) -- 높을수록 좋다.
• Service interruption: MTTR(mean time to repair) -- 낮을수록 좋다.

--> MTBF(mean time between failures) = MTTF + MTTR

Availability

 

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Disk Storage

Disk Storage

 

Disk Sectors and Access

Disk Sectors and Access

 

Disk Access - Example

Disk Access - Example

--> Average read time에서 seek time의 영향력이 크다!

 

Disk Performance Issues

• Average seek time을 줄이기 위한 방법: Locality and OS scheduling lead to smaller actual average seek times. 
• Disk controller: allocate physical sectors on disk.
• Disk drive: include caches.

 

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Flash Storage

Flash Storage

• NOR flash
• NAND flash

 

 

 

 

 

출처: 이화여자대학교 이형준교수님 컴퓨터구조