Magnetic Tape Deterioration and Data Recovery 5. DATA RECOVERY As we said earlier, there are three stages in the tape deterioration process, and modern high speed, vacuum tape drives are not suited for reading tapes with any problems other than those at stage one (i.e. corrected and uncorrected errors). In some cases they can infact cause irrecoverable damage to the tape - the tape can stick to the drive head, the capstan, or the vacuum chamber as it is being read, and oxide can be stripped off the tape. Once this has happened, no amount of tape recovery can put back data from the section of tape with missing oxide. Various techniques have been developed for recovering data from deteriorating tapes. The system that we have developed, after running a series of laboratory tests in conjunction with a tape and cartridge manufacturer, for "sticky" tapes (i.e. at stage two of the deterioration process) is as follows: 'Dry' the tapes in a temperature controlled environment for at least 24 hours. Allow the tapes to cool back down to room temperature. Clean and retension the tape on a tissue tape cleaner using a slow rewind option. This means that the tape will be less compacted on the spool than from normal high speed rewind. Read the tape on a custom modified, variable speed, tension-arm tape drive. Use interactive software. The combination of the modifications to the tape drive and the use of interactive software, allows the operator to stop reading the tape between records and clean the head when necessary. For tapes that have deteriorated further (i.e. stage three in the deterioration process) and are no longer sticky but instead the oxide is peeling off the tape, a different recovery method is necessary. Here the tapes do not need any drying and they should not be cleaned as this will only result in more oxide being removed. The operator essentially has one opportunity to recover as much data as possible by reading the tape slowly (one record at a time in some cases) and cleaning the head regularly. As data recovery specialists, we receive a lot of problem tapes in poor condition - we have recovered data from hundreds of thousands of tapes from many countries around the world. Although we cannot always achieve 100% data recovery, the success ratio is very high. Table of Contents INTRODUCTION TAPE MANUFACTURING PROCESS TAPE DETERIORATION DATA AUDIT DATA RECOVERY SUMMARY See other technical papers.