What is Data Loss ?
In today's scenario, no organization can survive without data. Data can be in the form of a small file to a big database. The quantity of mission critical information that organizations are storing, managing and maintaining on computers is growing at an exponential rate.
With the explosion in data comes an increased potential for data loss. And data loss is the synonym for destruction. For this reason, it is the most dreaded term computer users know or do not want to
Its only when data loss occurs that one realizes that "DATA is the Most Expensive (Priceless)" part of the computer.
Data Loss is said to have occurred when
Hard Disk does not boot by itself, and does not go to the DOS (C: or D: etc) drive.
The directories are not listed.
Files are not getting executed, opened or copied.
Files/folders are missing.
This can be due to logical or physical problems on the disk.
HARD DISK CASES
When is a disk said to be Physically Bad?
Disk not being detected by the system setup.
Detected but a lot of noise (clicking or hissing) is emanating from the disk.
Head is jammed and is not able to read anything from the disk.
Large number of physical bad sectors are present on the disk.
When is a disk said to be Logically Bad?
A disk is said to be logically bad if it is detected by the motherboard but system displays errors like:
Invalid drive specification, Invalid partition table, Missing operating system, ROM basic error, Drive not ready, Invalid media type error, Sector not found, Data error reading file, VFAT error, File allocation table damaged, File not found/missing or deleted accidentally.
The causes of these errors could be because of varied reasons as virus attacks user negligence faulty software functions incorrect shut downs voltage glitch partition corruption hard disk failure, deleting files, accidentally formatting drive, incorrect data transfer, incorrect method of backup etc. are also the reasons of data loss.
What is Data Recovery?
It may not be what you think it is!
Many people equate data recovery with restoring data from a tape backup, or use the term “ data recovery” interchangeably with “ disaster recovery” as in recovering from a major disaster such as a flood, fire or bombing attack. These meanings are quite true in the general sense and “data recovery” is usually one step of “disaster recovery” process.
However, the term “Data Recovery” has a very specific meaning in the computer industry. “Data Recovery” is the act of obtaining usable data from downed computers and backups and corrupted or deleted file-sets.
Data recovery cases can be divided into two broad categories:
Involve single hard drives form a PC, MAC or Notebook or removable media such as a photo card or zip disk.
Involve hard drives, RAIS arrays, tape and optical media or corrupted databases and files systems usually from multi-user, business systems. Data storage at the high-end has become a very complex field. In the case o f these complex situations data recovery can be seen as “ troubleshooting data storage” .
Whether common or complex, each data recovery case is unique and the process can be very resource intensive and exceedingly technical.
100% Data Recovery is Possible if
Errors like Invalid partition table, Invalid media type error, Invalid drive specification, general failure reading drive etc are displayed or the problem with Partition Table, Boot Sector and Root Directory. Files are accidentally deleted. Disk has been formatted and small files are to be recovered. Chernobyl (April 26 virus attack). Crash due to any boot/partition corruption.
Do's and Don'ts of Data Recovery
Switch off the computer as soon as data is lost, whatever reason it may be. Users still keep working on it thinking they will recover it later. A file deleted from a folder is physically present there and only its entry from FAT/MFT is reset. The deleted file will be there until it is overwritten. Even if you copy some data to another folder, this deleted file may get overwritten! A folder may be somewhere and files under it may be somewhere else, they are linked by the FAT/MFT. Viruses may infect a computer today, but they attack the system many days later or even years later. They require this time for spreading themselves. Some people think that their system has crashed because a virus came at that time only. Not all viruses corrupt data files. Most viruses corrupt only system files and partition etc. Data can be recovered in such instances too. When a disk does not boot, some think that using FDISK to create new partition will bring data back. But this will cause even more damage to data. People think data cannot be recovered after formatting a disk or changing partition. High level formatting will only reset the FAT and root directory on the disk, but data area remains intact, only to be recovered by experts like us The recovery CD provided by many computer manufacturers is not for recovering data, but only for automatically formatting the disk and automatically re-installing the operating system etc. Never, ever, attempt to open your hard disk drive by yourself because breaking the seal can damage many drives beyond repair, making your ability to recover data completely non-existent. Take back up of your hard disk at regular short intervals.