Recovery from media failures and tape damage

Media Flaws, or medium errors, result from faults with or damage to the physical media, or from problems during the recording. They can be caused by over use, degradation of the recording surface due to media decay, or problems with the tape drive at the time the backup was made. In many cases data recovery is the only option for regaining access to the data from the tape.

These are example typical media flaw or media error issues where a tape data recovery has been successful

Data Recovery from a tape with media flaws

Once a media flaw or medium error has been manifested, either in the form of an error or warning reported by the backup software during data restoration, or the behaviour of the tape drive (in particular drive cleaning lights becoming illuminated, or there are audible repeated read attempts), it is imperative that any further use of the tape is kept to a minimum.

Continuing use of the tape when media errors are being reported can result in increased tape errors leading to further loss of data, where there is physical damage the tape might snap and the result can be that a considerable length of tape becomes damaged and the data on it is lost.

At Altirium we do not rely on the originating software to restore data and our focus is to secure any recoverable data a quickly as possible. The recovery software we develop, allows us to overcome many of the problems presented by media flaws and to recover the maximum amount of data available.

Once the data from the failing tape has been secured it is then possible for us to locate and recover your critical data.

The effect of media flaws and damage

Whilst creased or snapped data tapes can clearly be seen to be damaged, media flaws on data tapes are not always humanly visible. Media flaws often only manifest themselves once you try and read the only copy you have of critical data from the tape. Less visible media flaws commonly occur due to excessive use and usually near the beginning of the tape as this is the most frequently accessed area of the tape. A poor storage or working environment can also cause media related problems, for example if tapes are stored in an excessively humid environment.

When backup software encounters a media flaw it will, in the majority of cases, stop and report an error. Data beyond the point of the flaw often cannot be accessed even though the remainder of the recording, and the files stored therein, might not have suffered any damage at all.

The illustrations show the impact a physical media flaw, such as a crease that spans the full width of the tape, can have on the different types of recording helical scan and serpentine. On tape that uses a helical scan recording method, such as AIT or DAT, once beyond the media flaw, the remaining data on tape is usually fully recoverable. With serpentine recording however, damage to the data occurs in multiple positions throughout the backup as the read heads pass over the same area of tape multiple times.