Protocol violated


I am offitially screwed. Last night I wanted to reinstall my laptop (which is also my only computer now), so I backuped the contents of my laptop's hard drive to an external usb hard drive as a 13 Gb tar.gz file and happily went on with a format and reinstall.

Of course, when I had completed the installation and went back to unpack files from the backup, I was greeted by a nice message from gunzip - "invalid compressed data--format violated".

Currently I am trying to follow gzip recovery guide that requires one to manually find the next undamaged compression block and make a new gzip file with standart header and then the undamaged compression blocks, but it is quite possible that data after that will also be damaged. Additionally I have no idea how tar will react to me giving it a middle of the archive, hopefully it will not get too confused. Unfortunately the damaged block is only 90 Mb into the 13 Gb file.

Oh, and of course there is a huge heap of really important files that I have no backup for that are on that backup. Fun, fun, fun.

Update: I have managed to recover two crucial documents from the formatted filesystem using Magic rescue and now I am proceeding with finding if I can recover anything from the .tar.gz backup file using Gzip recovery toolkit. It is buggy, but it is still better then doing it by hand.

Unfortunately, I also found out about some kind of hardware problem with my external harddrive - if I transfer lots of data to it (think a direct copy of a 13 Gb file), then it just locks up and stops responding until I power cycle it. If I turn off the USB2 support, then it works reliably, but very very slowly. This slows down my recovery attempts even more.

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karlfr 13 years, 11 months ago

Synchronicity. I just tarred 3Gb of data, and deleted the original files. While the deletion was *in progress*, I read your post on Planet. What's the probability of such a thing? I hope you recover yours, and I hope I don't need to recover mine.

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Ben Hutchings 13 years, 11 months ago

When I first used an external hard disk with USB 2 I would get an I/O error after a while which caused the filesystem on the external HD to go read-only. The fault there was in the controller, not the disk enclosure. So it might be worth trying a different controller - or a different cable (USB 2 High Speed needs a higher standard of cable than original USB).

I don't know whether tar will be able to resynchronise if there is some "junk" between files, but it should not be too difficult for you to identify the next file header and restart from there as tar formats are pretty simple.

Link | Reply » Apple's Time Machine: 13 years, 10 months ago

[...] Hello? rsync and rdiff, anyone? Not to mention a host of proprietary applications which incorporate similar features. Gnome developer Miguel de Icaza points toward Dirvish as a Linux-based program that has similar features. It looks okay, but spending time using Windows and Mac OS X has spoiled me - I require my Linux applications to have nice GUIs, like Beagle, the equivalent of Spotlight in OS X (see right). SBackup, a Python-based Google Summer of Code 2005 Project could have been this application, but there have been no code changes for four months. I would say that it was humorous that he would write about his backups being corrupted in late June, except data loss is never funny. [...]

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