data recovery gyan

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What do we mean by data recovery? Data recovery is the process of retrieving data from damaged, failed, corrupted, deleted or inaccessible storage media (hard drives, removable media, Pen Drive, SSD, CD’s, DVD’s, Blue Ray Discs, RAID, Storage Tapes, etc...) when it cannot be accessed normally. Recovery may be required due to logical damage to the file system or due to physical damage to the storage that prevents the media from being mounted or detected on the host OS.

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Page 1: Data Recovery Gyan

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What do we mean by data recovery?

Data recovery is the process of retrieving datafrom damaged, failed, corrupted, deleted orinaccessible storage media (hard drives, removablemedia, Pen Drive, SSD, CD’s, DVD’s, Blue RayDiscs, RAID, Storage Tapes, etc...) when it cannotbe accessed normally.

Recovery may be required due to logicaldamage to the file system or due to physicaldamage to the storage that prevents the mediafrom being mounted or detected on the host OS.

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So, basically there are three types of crashes:

1.Logical crash.2.Physical crash.

3.Logical cum physical crash.

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A logical crash or a logical damage is mainlycaused because of the following reasons

power surge, that makes file system inconsistentwhich in turn crashes the system and makes the

data inaccessible.Virus attacks (file damaging virus or file systemdamaging viruses)

Malfunctioning of OS or Application software orencryption software.

Accidental deletion of data

Sabotage (Somebody Intentionally deletes thedata)

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In case of physical crash, most of the time PC isunable to detect the media and this is causedbecause of the following reasons.

Media Head Assembly damage

Electronic failure i.e damage on PCB

Motor failure or Motor Jam

Firmware Corruption which makes the Harddisk inaccessible.

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The third type of crash is Logical cum physicalcrash which is caused due to

the development of bad sectors because of weakMHA

Problem on the platters.

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Encryption is as old as the art of communication, Itis the process of transforminginformation (referred to as plain text) using analgorithm to make it unreadable to anyone exceptthose possessing special knowledge, usuallyreferred to as a KEY. So it is considered as one ofthe most effective way to achieve data Security.

Unencrypted data is called Plain text

 Encrypted data is referred to as cipher text.

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Some of the most commonly used third partyencription softwares are

Safe Guard Encryption

Safe Boot Encryption

EPHD( Encryption Plus for Hard Disks )

PGP(Pretty Good Privacy )

Point Sec. Encryption

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RAID (Redundant Array of Independent Disks):-

It is an array of multiple independent hard diskdrives that provides high performance and faulttolerance.

RAID combines two or more physical hard disksinto a single logical unit by using either specialhardware or software. Hardware solutions oftenare designed to present themselves to the attachedsystem as a single hard drive, so that the operatingsystem would be unaware of the technicalworkings

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1.RAID 0 :-

RAID 0 (striped disks) distributes data acrossseveral disks in a way that gives improved speedand no lost capacity, but all data on all disks willbe lost if any one disk fails. Because data on thiskind of RAID configuration stores in the form ofstrips. Like

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2.RAID 1:-

RAID 1 (mirrored disk setting) duplicates dataacross every disk in the array, providing fullredundancy. Two (or more) disks each storeexactly the same data, at the same time, and at all

times. Data is not lost as long as one disk survives.Total capacity of the array equals the capacity ofthe smallest disk in the array. At any given instant,the contents of each disk in the array are identical

to that of every other disk in the array. So this kindof RAID called Mirrored Disk Array. Like

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3.RAID 5:-

RAID 5 (striped disks with parity) combines three

or more disks in a way that protects data againstloss of any one disk; the storage capacity of thearray is reduced by one disk. Parity of this kind ofRAID process in the form of Diagonally.

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4. RAID 6:-

RAID 6 is a “Striped set with dual distributedparity”. Provides fault tolerance from two drivefailures; array continues to operate with up to two

failed drives. In this kind of RAID structure twohard disk for the parity and in that hard disk XORof the data and parity stored. So chances of recoverthe data are more in this kind of RAID. Structure

of RAID 6 is like:-

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STRUCTURE:-

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5. RAID 10:-

RAID 10 (or 1+0) uses both striping and mirroring.

"01" or "0+1" is sometimes distinguished from "10"or "1+0": a striped set of mirrored subsets and amirrored set of striped subsets are both valid, butdistinct, configurations.