Intelligent disk subsystems overview



This system optimize all available storage solution automatically

Data must be automatically placed and stripped across multiple physical storage resources, including arrays, RAID groups, Disk types and Controllers.

Four main components:
  1. Front End
  2. Cache
  3. Back End
  4. Physical Disk

Front End:

Interface between host and storage system.
Consist of two components
  1. Front End Ports: enable host to connect to intelligent subsystem
  2. Front End Controllers:  is used for routing data from cache using internal bus.
Uses command queueing algorithm for I/O processing.


Improves performance
Made up of semiconductor memory.
Holds data for temporary purpose to reduce time required to service I/O request from host.

Structure of cache:
  1. Organized into pages
  2. Consist of data store and TAG RAM.
  3. Track of each address line is recorded via Tag RAM
Read Operation:
  1. Host sends read request, front end controllers search tag ram to determine required data is available in cache.
  2. Cache hit data is found on cache while cache miss data is not found in cache but in main memory.
  3. In case of miss read policies are:
    1. Read through
    2. No read through

Write Operation:

Policies are:
  • Write through cache
  • Write back cache

Back End:

1. Interface between physical disk and cache
2. Controls data transfer
3. Two components:
  1. Back end ports
  2. Back end Controllers

Physical disk:

1. It stores data persistently.
2. Disks are connected to back end with either SCSI or a fibre channel.
3. Logical Unit Numbers(LUN) are used for identifying virtual hard disk patterns.

Python Programming ↓ 👆
Java Programming ↓ 👆
JAVA covered following topics in these notes.
JAVA Programs
Principles of Programming Languages ↓ 👆
Principles of Programming Languages covered following topics in these notes.

Previous years solved papers:
A list of Video lectures References:
  1. Sebesta,”Concept of programming Language”, Pearson Edu 
  2. Louden, “Programming Languages: Principles & Practices” , Cengage Learning 
  3. Tucker, “Programming Languages: Principles and paradigms “, Tata McGraw –Hill. 
  4. E Horowitz, "Programming Languages", 2nd Edition, Addison Wesley

    Computer Organization and Architecture ↓ 👆

    Computer Organization and Architecture covered following topics in these notes.

    1. Structure of desktop computers
    2. Logic gates
    3. Register organization
    4. Bus structure
    5. Addressing modes
    6. Register transfer language
    7. Direct mapping numericals
    8. Register in Assembly Language Programming
    9. Arrays in Assembly Language Programming


    1. William stalling ,“Computer Architecture and Organization” PHI
    2. Morris Mano , “Computer System Organization ”PHI

    Computer Network ↓ 👆
    Computer Network covered following topics in these notes.
    1. Data Link Layer
    2. Framing
    3. Byte count framing method
    4. Flag bytes with byte stuffing framing method
    5. Flag bits with bit stuffing framing method
    6. Physical layer coding violations framing method
    7. Error control in data link layer
    8. Stop and Wait scheme
    9. Sliding Window Protocol
    10. One bit sliding window protocol
    11. A protocol Using Go-Back-N
    12. Selective repeat protocol
    13. Application layer
    1. Andrew S. Tanenbaum, David J. Wetherall, “Computer Networks” Pearson Education.
    2. Douglas E Comer, “Internetworking with TCP/IP Principles, Protocols, And Architecture",Pearson Education
    3. KavehPahlavan, Prashant Krishnamurthy, “Networking Fundamentals”, Wiley Publication.
    4. Ying-Dar Lin, Ren-Hung Hwang, Fred Baker, “Computer Networks: An Open Source Approach”, McGraw Hill.