50 Ways to Lose Your Data

16 02 2009

So I’m rebuilding my server

I figured I’d better get backup going early.  So I went to look at my github project and it was clearly incomplete (Python syntax error).  Yet I *had* done a complete successful backup already, so there must’ve been a good copy of the script on Hydra before the rebuild.

At the beginning of this, I archived a bunch of stuff from that server in a tarfile on an external disk.

To be sure the tar worked, I had re-run the same tar command
piped into md5 and then checked that against the md5sum of the .tar file

The first time around, it failed.  I presumed that was due to some
bitrot on the target disk, so I did the whole procedure again.

This time the md5s matched, and  I stored the checksum in a file alongside the
tar file.

But somehow, now tar can’t read the .tar file!

tar: This does not look like a tar archive
tar: Skipping to next header
tar: Archive base-256 value is out of time_t range
tar: güg: implausibly old time stamp 1969-12-31 18:59:59
tar: Skipping to next header
tar: Error exit delayed from previous errors

And, yes, the md5s still match! I probably should have tried to read the tar file the moment I created it. Bah.

So I figured I might grab the backed up script from the Amazon bucket that stores our backups.  But that backup was apparently encrypted with a public key that I can’t
identify, and don’t remember the passphrase for!  Probably that was a key I
generated especially for root’s backup process on the server, and the only record is probably locked in that tarfile.  Even if I could read that, I still wouldn’t know the passphrase :(.  How do people keep track of all the unique and frequently-changing—yeah, right!— passwords they’re supposed to have anyway?

So I’m giving up on all that data in the tar file for now (what else can
I do?) and I’m back to trying to reconstruct a working backup script.

Get a new plan, Stan!




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