|
Recovery of data from overwritten tapes
Altirium use modified hardware and specialised recovery techniques to gain access to previously recorded data stored on the tape. Once the data can be accessed and read from the tape the recovered data then requires further processing to restore the original files that were backed up.
In most cases the data on the tape is stored in a proprietary format that can be understood only by the backup software. The overwriting will have destroyed some data and so the recovery will be of an incomplete backup, this data will not be recognised be the backup application so the recovery work required will be more than just writing the recovered data out to a replacement tape for the backup application to deal with.
At Altirium we develop software that allow us to restore files from proprietary backup formats. This gives us the capability to deal with problems that may occur within the data, and to develop solutions for new formats as and when they arise.
Tape overwriting
Whilst data that has been physically overwritten cannot be recovered. It is still possible to recover beyond newly recorded data.
Above: Recoverable data from overwritten helical scan recording.
Above: Recoverable data from overwritten serpentine recording.
Unlike video tapes, that play from start to end of tape regardless of any new or old recording, most data storage tape technologies prevent access to previously recorded data beyond the new recording. This can include the encoding of data to denote end of recorded data (EOD), the setting of write pass values within the data so that any older data that is encountered will be discounted, and the storing of information about the number of currently valid blocks of data on the tape. The data recovery process requires the ability to work around these obstacles.
