Recovery Tips

Recovery FAQ

Data Recovery: What is Data Loss A data loss situation is usually characterized by one (or more) of the following:
o The sudden inability to access any data from a previously functioning computer system or backup.
o The accidental erasing of data or overwriting of data control structures.
o Data corruption or inaccessibility due to physical media damage or operating system problems.

Data loss can be caused by physical damage or "soft" (logical) problems. For example:
o A personal user can no longer access the "C:" disk on their PC or no longer read a floppy disk.
o A corporate data server has crashed and no longer serves data to the corporate network.
o A set of medical images backed up on a digital tape cartridge can no longer be restored.

Have you experienced data loss?
If your answer is "yes", then you are not alone! The majority of computer users will encounter this situation at some time.

Physical Causes of Data Loss
Approximately 70% of data loss cases were caused by physical problems. Occasionally manufacturing defects or design flaws can cause mechanical or electronic failures. Most physical problems can be traced to other root causes.
Physical problems include mechanical failures due to:
o Shock from device being bumped, dropped or moved while operating causing a head crash or platter misalignment.
o Device exposed to extreme cold temperatures and/or rapid temperature change prior to use. For example powering up a laptop after being in a freezing car overnight.
o Disasters such as flood, fire (including sprinkler-water secondary damage) and explosion.
o Stiction: The read-write head assembly gets "stuck" on the disk media due to deterioration of the lubricant or because it has failed to retract to its rest (parked) position.

Physical problems also include failure of electronic components on the disk's controller board due to:
o Electrostatic Discharge (ESD) or heat.
o Power loss or power surge.

Physical problems affecting the computer equipment may also render data inaccessible even though the media (that it is stored on) still functions perfectly:
o Sudden power loss may corrupt open database files.
o Computer memory glitches may result in bad data being written to sensitive filesystem control areas.

Soft Causes of Data Loss
"Soft" causes in this context means non-physical causes. These are also referred to as "logical" causes. Soft problems can usually be related back to something that someone did or did not do, in other words "human error". Oops! o Accidentally deleting files or reformatting the system.
o A tape containing a good backup was partially overwritten because it was inserted out of sequence during a tape rotation.
o "Failed restore". Restoring from a backup can be a lengthy and error prone process. This can include tape format or compression errors.
o Viruses. The malicious work of a smart sociopath.
o Configuration errors due to the complexity of the system.


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 the "disaster recovery" process. However, the term "Data Recovery" has a very specific meaning in the computer industry. First, consider one of the dictionary's definitions for "recovery".
"Recovery" noun.
"The act of obtaining usable substances from unusable sources."
Based on this, we offer the following definition.
"Data Recovery" noun.
"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:
Common Recoveries
Involve single hard disks from a PC, MAC or Notebook or removable media such as a photo card or zip disk.
Complex Recoveries
Involve hard disks, RAID arrays, tape and optical media or corrupted databases and file systems usually from multi-user, business systems. Data storage at the high-end has become a very complex field. In the case of 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.