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Archive for the ‘Tape Restoration’ Category

Festive fun with LTO

‘Twas the night before Christmas, when all thro’ the house
Not a creature was stirring, not even a mouse;
Save for the IT manager at a German TV channel attempting to restore some footage from their PresStore backup archive in time for a New Year ’s Day TV Show…

To this day we are not sure what was not working, but working it was not. The catalogue of the PresStore backups had been cleared, it was thought that the 200 x LTO4 tapes would no longer be needed, so now a frantic effort was being made to re-create the infrastructure and scan 200 tapes.

With a single LTO4 drive it was already going to be a matter of luck whether the right tape was found in time as even working 24 hours a day you could hope only to get through 40 or so tapes in the time available, and the re-cataloguing kept failing with configuration errors, and so came the call for help, followed by an IT manager in a Volvo bearing LTO tapes and an expression of angst.

One of the benefits of writing one’s own software for various backup formats is that you don’t need to worry about configuration, processing is pretty much a function of tapes drive numbers, and with 20 LTO5 drives running in less than 2 days the PresStore backups had been re-scanned, a catalogue created and the required data identified.

Restoration of the required data from the PresStore backup took about an hour and so with time to spare our hero was racing back under the channel to save the day.

I have no idea who the footage was of, someone I am too old to appreciate I am told, so I apologise now to any Bavarian parent whose New Year peace we were responsible for disrupting, but the happy smiling face of the IT manager made it all worthwhile.

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Unlucky 13?

Being a generally optimistic person and not believing in bad luck, not even if someone turns up with an OnStream cartridge, the prospect of 13 x LTO2 tapes containing ARCserve backups was not of particular concern. Then the additional information was provided, they had been to another company for restoration and there was a problem with the data, the backups were corrupted and could not be restored, “was there anything we could do”?

Not having seen the tapes it was not honest to give more than a cautiously optimistic opinion. No-one here had encountered a corrupted ARCserve backup since some problems with Adaptec 1542 cards and MSDOS with too much memory installed back in the early 1990s. It seemed more likely we would find that they were either not ARCserve at all, or else were encrypted.

When the tapes arrived it all became clear. They were ARCserve with multiplexing, which means that the backup data from several backups can be interleaved and any attempt to proceed in a linear manner without first loading and interpreting the ARCserve MUX (multiplex) tables is going to end in tears, or at least with worthless data. The next challenge was restoration within an average life-span, restoring a single backup would be relatively straightforward one the MUX tables had been correctly interpreted, but with over a hundred backups per tape the idea of restoring one set at a time was not overly appealing as each tape would have to be read over 100 times, effectively turning a 13 tape restore into a 1300+ tape restoration exercise. This is where the benefits of developing software for tape restoration come to the fore, and being able to modify code to enable the simultaneous processing of all backups so each tape took less than 3 hours to read.

Once the tapes had been catalogued the required Exchange email data was located. Anyone fancy a guess at which number tape it was on? Sorry, that would have been too poetic, it was on tape 7.


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