Skip to main content

RAID technology | DBMS - Computer science tutorial point


RAID (Redundant Array of Independent Disk)Technology


l A natural solution is a large array of small independent disks acting as a single higher-performance logical disk. A concept called data striping is used, which utilizes parallelism to improve disk performance.
l Data striping distributes data transparently over multiple disks to make them appear as a single large, fast disk. 

    Different raid organizations were defined based on different
    combinations of the two factors of granularity of data
    interleaving (striping) and pattern used to compute redundant
    information.
l Raid level 0 has no redundant data and hence has the best
     write performance.
l Raid level 1 uses mirrored disks.
l Raid level 2 uses memory-style redundancy by using
    Hamming codes, which contain parity bits for distinct
    overlapping subsets of components. Level 2 includes both
    error detection and correction.
l Raid level 3 uses a single parity disk relying on the disk
    controller to figure out which disk has failed.
l Raid Levels 4 and 5 use block-level data striping, with
    level 5 distributing data and parity information across all
    disks.
l Raid level 6 applies the so-called P + Q redundancy
    scheme using Reed-Soloman codes to protect against up
     to two disk failures by using just two redundant disks.
Use of RAID Technology 
Different raid organizations are being used under
different situations
l Raid level 1 (mirrored disks)is the easiest for rebuild of a disk from other disks– It is used for critical applications like l
   Raid level 2 uses memory-style redundancy by using Hamming codes, which contain parity bits for distinct overlapping subsets of components. Level 2 includes both error detection and correction.
l Raid level 3 ( single parity disks relying on the disk controller to figure out which disk has failed) and level 5 (block-level data striping) are preferred for Large volume storage, with level 3 giving higher transfer rates.
l Most popular uses of the RAID technology currently are: Level 0 (with striping), Level 1 (with mirroring) and Level 5 with an extra drive for parity.
l Design Decisions for RAID include – level of RAID, number of disks, choice of parity schemes, and grouping of disks for block-level striping.  

Labels:

Comments

Post a Comment

please subscribe my blog and let me suggest how I improve this site

Popular posts from this blog

type casting in C. - computer science fundamentals tutorial

Typecasting in C Typecasting is also known as "forced conversion". It refers to changing variable one data type to another data type.          Typecasting in can be certified into following two types: - 1) Implicit type casting. 2) Explicit type casting. Implicit type casting : - It is also known as "Automatic type conversion". It is done by compiler on its own without any external trigger from user. Generally takes place when in an expression more than one data type is present in such condition. Type conversion take places to avoid data lose. Example : - #include<stdio.h> main() {   char y = 'a';   int b = y; printf("%c",y); printf("%d",b); } Explicit Type casting : - This process also called 'Type casting' and it is user defined . Here the user can type cast the result to make it of particular data type. Example : - #include<stdio.h> main() { int m
2 comments
Read more

Important MCQ of RDBMS( Relational database management system)-FCST

Important MCQ of RDBMS  1. A RDBMS consists a collection of ? a. Tables b. Fields c. Records d. Keys  ANS/- a. table 2. The term attribute refers to a ___________ of a table a. Record b. Tuple c. Column d. Key   ans/- c. Column 3. In relational model, the row of table is known to be ?  a. Relation b. Entity field c. Tuple d. Attribute  ans/- C. Tuple 4. . Address field of a person should not be part of primary key, since it is likely to ? a. Dependent b. Too long c. Changed d. Not changed  ans/- c. Changed 5. The relational model is concerned with ? a. Data structure and Data integrity b. Data Manipulation c. Both a and b d. None of these  ans/- c. Both a and b 6. Which is the false statement from the following ? a. A veiw is a named derived table b. A name relation is variable c. A veiw is a named reation and is virtual d. None of these  ans/- d. None of these 7. The union of primary keys of the related entity sets becomes a
6 comments
Read more

Solve-write C program to find grade of student by using nested else-if statement

C program to find grade of student by using nested else-if statement Problem Description This program take input as your number then show your grade. Problem Solution 1. enter your marks as input. 2. then check your marks with 'If' block's condition. if it satisfied then show your grade as output. 3. if it not satisfied then it checks with all else-if block's condition repeatedly. 4. print the grade according to your given marks as input and exit. Program codes:-   #include<stdio.h> main() { int n; printf("\n enter the marks:"); scanf("%d",&n); if(n>89) printf("O"); else if(n>79) printf("E"); else if(n>69) printf("A"); else if(n>59) printf("B"); else if(n>49) printf("C"); else if(n>39) printf("D"); else printf("F"); } Program explanation:- 1. enter your marks. for example we take 70 .
Post a Comment
Read more