Tape Data Recovery - What's The Difference Between Physical and Logical Recovery?
Tape data recovery is the recovery of data that has been lost on a tape, obviously. A tape cartridge can be damaged in any number of ways from smoke to water to dropping the cartridge. Tapes can also be damaged by exposure to extreme temperatures, internal mechanism failure, and errors that are located in the middle of the tape's file among other things. Tape data has been recovered from tapes with water damage, missing oxide, folds in the tape material, sliced edges, blade damage, no oxide, bad oxide, and friction damage. There are generally two types of tape data recovery. These are known as physical recovery and logical recovery.
1. Physical Recovery
Physical tape data recovery is needed when there is actual physical damage to the tape itself. Something is physically wrong with the plastics or the cartridge itself and this prevents the data on the tape from being read properly. This type of recovery could be needed because of the deterioration of magnetic coatings on the actual tape surface, broken or cracked wheels or cartridge housings, twisted or folded tape, creased tape edges, broken tape, stretched tape, or any other reasons associated with the actual tape of the machinery.
In general... tapes are generally used for backup purposes. In systems where high reliability is critical, primary data storage is generally on some type of RAID system. So RAID data recovery is generally more common than tape data recovery. But... tape recovery is at time needed.
Many places that deal in tape recovery promise a high recovery rate from the physical factors, usually over 98 percent which means that the trained professionals are pretty confident in their work. So if you have dropped your tape in the mud, water, or had it fall into any other materials and feel that it may be too damaged it is good to remember the high success rate of most tape recovery services. Just get your equipment to them as sooner rather than later.
2. Logical Recovery
On the other hand, logical tape data recovery is somewhat more complicated. Because of the complexities, it is generally more expensive. Logical recovery is needed when data that was successfully recorded on the tape cannot be read for some unknown reason or set of circumstances that do not involve an actually visible form of damage to the tape and the tape body.
The recovery of files in logical recovery requires the technician to use multiple versions of tape recovery software and take many "passes" at the tape using it. Normally, the file can magically be pieced back together but the success rate of logical data recovery in the world of tapes is lower than it is when involving physical recovery.