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DLT tape recovery - can data be recovered after an overwrite?
Posted by Mark on Nov 21, 2008
Interesting data recovery job this one, most especially as it had been sent to three other companies in continental Europe before it found its way across the moat to dear old blighty.
The data on this tape was an Amanda backup from a Sun UNIX system, in the region of 80GB had been written to an SDLTII data cartridge for safekeeping, but no-one had set the tape to write protect. Consequently, when one of the IT staff went to recover some data from the tape, something went wrong and the DLT was re-initialised. From being a vital system backup brimming with data ready to be accessed, the DLT was just another scratch tape waiting to be used. Needless to say the accounts department who needed the data were non-too happy when their data could no longer be restore.
Throw the tapes away - disk backup is here
Posted by Mark on Oct 29, 2008
Data backup can be a nightmare, balancing the demands for instant access against the equally important need for security and reliance. Essentially there are Business Continuity demands that are competing with the requirement to be able to perform a Disaster Recovery.
The same people that patted you on the back because they could get their files back quickly from an online storage system might be the first in the queue to stick a metaphorical knife between your shoulder blades when the disk based backup system is off with the data recovery company, and you don’t have a good old fashioned solid and reliable tape backup.
So are tape backup systems better than disk based virtualized backup systems, do on-line backup systems trump all others? What is best?
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Who Said Tape Was Not Reliable?
Posted by Mark on Oct 23, 2008
Another tape recovery story, but one that shows an impressive level of resilience on the part of an old tape technology. The tape in question was a TK50, leading edge back sometime in the 1980s (and notably the technology from which DLT was developed) and after 20 years of being used each day as the boot media for a manufacturing system it had finally given up and a data recovery was needed.
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Catch-22, or “don’t keep the only copy of the software on the tape”
Posted by Mark on Oct 20, 2008
Ever had one of those days where having tried to do everything correctly that nasty stomach churning feeling becomes overwhelming as you realise that there is a major problem and a simple restore could now be a major tape data recovery issue.
You have the backup tape, you have the tape drives, but the only copy of the backup software is within a backup set on the tape and this backup is from 14 years ago and the software is not sold any more.
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The long and winding DLT
Posted by Mark on Oct 18, 2008
Tape is tough, but really …
As a data recovery engineer pretty well nothing comes as a surprise. We have received DLT cartridges where the tape has snapped, been overwritten, even where it has been submerged in flood water for over a week.
Nothing, though, has been quite as bizarre as the empty DLT case that arrived, along with a supermarket carrier bag crammed full of unwound tape. What was going on?
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Tape - dead man spinning?
Posted by Mark on Oct 14, 2008
Ever since I became involved in the sometimes arcane art of recovering data from tapes there has been the perpetual sound of people announcing that “tape is dead, long live the …”, promptly followed by a further advance in tape technology and the patient pulls through.
What is the future of tape? Why should we keep using it?
The Tale of the Tape
Posted by Mark on Sep 24, 2008
Well really the title should read, “The tale’s on the tape”
Computer forensic investigation stories tend to focus upon what has been found on so-and-so’s hard disk drive how, despite attempts to eradicate the incriminating data, the dastardly plot was foiled and we can all get back to the Malt bar and eat Scooby Snacks. But where else, other than the local hard drive, can the information you’re looking for be found.
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Look after your back-up tapes and …
Posted by Mark on Sep 23, 2008
… there is a chance they will look after you.
Care of backup media is an often overlooked issue, but why spend thousands each year on media and even more on the time and equipment to get your data on to it, then effectively risk throwing it all away by not paying attention to storage and environment?
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Once you are in a hole it is time to stop digging
Posted by Mark on Sep 23, 2008
“There is just one more thing we want to try” has sometimes been the sentence that I have heard from the other end of the phone immediately prior to some data being lost to this world forever.
This is not a plug for using data recovery companies, I work for one and don’t believe that it is always the best option, but it is a good idea to emulate the calm and measured approach that a professional would take.
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How to avoid Data Recovery
Posted by Mark on Sep 23, 2008
We often get asked “what could I have done differently” when data has been lost, especially when a recovery could not be made or the cost of the data recovery work was rather high.
The simple answer is often “made sure you had another copy of the data”. A hard disk crashing might result in annoyance, the cost of a replacement disk, the time to re-install the operating system and all of the applications, but this is nothing compared with the time that has been spent working to create spreadsheets and to write letters or other documents. Worse still is when the data is a record of an event that simply cannot be repeated, it is not possible to travel in time and go back over your children’s early years, and holding that wedding again is not usually an option.
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