A highly effective backup system would have duplicate copies of every file and program that were immediately accessible whenever a Data Loss Event was noticed. However, in most situations, there is an inverse correlation between the value of a unit of data and the length of time it takes to notice the loss of that data. Taking this into consideration, many backup strategies decrease the granularity of restorability as the time increases since the potential Data Loss Event. By this logic, recovery from recent Data Loss Events is easier and more complete than recovery from Data Loss Events that happened further in the past. Recovery is also related to the type of Data Loss Event. Recovering a single lost file is substantially different from recovering an entire system that was destroyed in a disaster. An effective backup regimen has some proportionality between the magnitude of Data Loss and the magnitude of effort required to recover. For example, it should be far easier to restore the single lost file than to recover the entire system. Initial steps upon data loss If data loss occurs, a successful recovery must ensure that the deleted data is not over-written. For this reason — one should avoid all write operations to the affected storage device. This includes not starting the system to which the affected device is connected. This is because many operating systems create temporary files in order to boot, and these may overwrite areas of lost data — rendering it unrecoverable. Viewing web pages has the same effect — potentially overwriting lost files with the temporary HTML and image files created when viewing a web page. File operations such as copying, editing, or deleting should also be avoided. Upon realizing data loss has occurred, it is often best to shut down the computer and remove the drive in question from the unit. Re-attach this drive to a secondary computer with a write blocker device and then attempt to recover lost data. If possible, create an image of the drive in order to establish a secondary copy of the data. This can then be tested on, with recovery attempted, abolishing the risk of harming the source data. See also Data spill Data truncation List of data recovery software References External links Data Loss Prevention Some Data Loss Event Computer data Data recovery