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DAT Data Recovery

Altirium's data recovery engineers have been dealing with DAT recovery work since the early 1990s. The types of problems have been varied ranging from physical damage, through to tracking and recording issues. We cannot hope to cover all permutations of problems that could be experienced but in general the ones detailed below cover most eventualities.

These are a few of the symptoms you might experience when there are reading problems with a 4mm DAT.

DAT Data Recovery Problems Explained

Drive lights flash, the cleaning light is illuminated and no data can be read.

The first action of a DAT drive once the tape has been threaded through the tape path is to read the system area of the tape. Crucially this tells the drive how the data is arranged on the media, notably how the tape is partitioned.

If there is a problem with the reading of the system area then the drive will work through its retry sequence, this includes unloading the cartridge and re-seating it to see if that corrects for the problem.

The cause of the problem could lie with the drive, which could require cleaning, but if no other tapes have been manifesting this problem then presume there could be a problem with the tape. If the tape does come ready then restore your critical data ASAP and back it up on to a good tape by using a known good drive.

If the tape will not come ready, even in a drive that you know is working properly, then data recovery is probably the only answer.

The restore process fails with a tape I/O error.

The DAT drive has encountered a length of tape where it cannot read data. Usually the failure will have been preceded by some noises from the drive and perhaps even an unload/load sequence. The cause of the problem could be physical, and this can usually be determined by the pitch of the sounds from within the drive. A crease, for example, results in a much smaller are of contact between the head assembly and the tape which causes a higher pitch sound from the drive.

A clicking or a buzzing sound is heard from the drive then the restore fails.

The drive contains a head cleaning mechanism. If the drive experiences difficulty when attempting to read data from a tape it actuates an arm in the end of which is cleaning material, this is to ensure that the read problem is not the result of 'head clog' which is when a build up of tape oxide blocks the read/write heads. The fact that the restore then fails indicates that this was not the problem and there is probably something wrong with the tape.

It is possible that a selective restore attempt might enable you to restore some of your most critical data but be cautious as any physical damage might be exacerbated with disastrous results.

The DAT drive lights keeps flashing but the tape will not eject.

If there is no attempt by the drive to unload and re-seat the tape, and no noisy self clean sequence then it is probably that the tape has either snapped or become detached from one of its reels. If the tape snaps then it is likely to become wrapped around the read head assembly and specialist help will be required to remove the tape without causing further damage so that the data can be recovered.

If the tape becomes detached at from either reel then there has been a serious internal failure within the drive as this takes considerable force. A light source and sensor pair detect the physical end or beginning of tape when the transparent leader tape passes and lets light through. If either component fails than damage can occur. It is unlikely that the tape will become entangled within the drive.

DAT records from the start to the end of tape and is not a serpentine format. This improves the prospects for tape data recovery, as once data can be accessed from beyond any damage the chances are good that the remainder of the tape can be read.

The DAT reports no data, or appears to contain the wrong backup set.

If it is the correct tape then this usually indicates that the tape has been re-used. The prospects for data recovery depend upon the extent to which the required data has been overwritten.

There is no way of positioning the media beyond the most recent data without retort to data recovery methods, and even if you could get into the old data your backup software would never understand what it found. A competent data recovery company will be able to recover all existing data and work on this to rebuild your files.

The tape is entangled in the drive and becomes severely creased

The drive has damaged the tape during either loading or unloading, most likely during unloading. You will have seen the drive going through its re-seating process to reload the tape and heard some quite alarming noises as the drive attempts self cleaning. To get the data back will require a data recovery service.

The recording technique used with DAT does improve the chances of a successful data recovery in many instances where there is physical damage. DAT records data from the start to the end of the tape, as opposed to serpentine formats where multiple passes along the length of the tape are made. This means that one the tape is positioned beyond the point at which a failure was encountered there is no reason for the drive to return to that point along the tape.

Last Updated (Tuesday, 30 June 2009 08:42)

 
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