Data recovery is the process of salvaging data from damaged, failed, corrupted, or inaccessible storage media when it cannot be accessed normally. This may include hard disks either desktop or laptop size, storage tapes, CDs, DVDs, raid array storage server ( raid 0, raid 1, raid 5 or multiple level raid 1 + 0, 5 + 0, 5 + 1, Flash memory card ( e,g SD card, XD picture card, MMC, compact flash ) for digital camera or handphone, PDA, USB thumb / pen drive and other digital storage. Recovery may be required due to physical damage to the storage device or logical damage to the file system that prevents it from being mounted by the host operating system.

Some common logical failure includes:

• Operating system failure
  
  
• Compromised or damaged file sysem or disk partition
  
  
• Partition table or MBR corruption
  
  
• Files accidentally deletion

Physical damage includes:

• Read-write head damage
  
  
• Failed spindle motor
  
  
• PCB board damage as a result of power surge
  
  
• Media damage as a result of fire, water

Most physical damage cannot be repaired by end users. For example, opening a hard disk in a normal environment can allow airborne dust to settle on the platter and become caught between the platter and the read-write head , causing new head crashes that further damage the platter and thus compromise data recovery process. Furthermore, end users generally do not have the hardware or technical expertise required to make these repairs. . Data recovery firms often use "Class 100" cleanroom facilities to protect the media while repairs are being made. Any data recovery firm without a C-100 clean lab will not be able to carry out such hardware related recovery on the hard disks.