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Okay, this has me totally stumped.

Background: I'm working on a cryptanalysis homework, trying to break a vigenere cipher with a 26 character key (a shuffled alphabet). Even though there are some 403 septillion possible keys, I tried a naive brute force approach... I mean, I could get lucky, I guess.

Problem/Question: I left a script running, generating 8 - 10 GB of data an hour, overnight. I figured the worst that could happen would be that it would fill my HDD. But something really weird happened instead: the directory my script was in (and writing data to) simply vanished. I checked it first thing in the morning and it was gone.

Everything was running in a subfolder of my, otherwise empty, home directory. My home directory remained, and the rest of the file system seems intact. Top showed my scripts still running. Fsck didn't produce anything useful.

I've been at computers for a long time and I've never seen anything like this (aside from a hardware failure, which I'm mostly sure this is not). Ext4 should support files up to 16TB in size, which far exceeds the capacity of the disk (500ish GB).

So, like I said, I'm stumped. Anyone have an idea as to what happened?

Harrison Pickett
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  • How did you conclude the directory is gone? If you script produces thousands of files you might be running into limitations of the program you're using to read said directory. – lcd047 May 04 '15 at 17:04
  • It isn't there when I do ls or find. df tells me that my entire system is 53GB... considering I have debian 8 installed, including several DEs, some development libraries, etc... and that I had nearly 20GB of data in the project directory when I left it... I'm pretty sure it isn't there.

    If I'm missing some other way to list directory contents, let me know.

    Oh, and 'otherwise empty' is a misnomer... I do have a hand full of dot files that are all intact... including my .ssh directory with my public keys (otherwise I couldn't access the machine for the most part).

     – Harrison Pickett May 04 '15 at 18:44
  • My script appends to a single txt file... and like I said, I should be able to keep a single file up to 16TB with ext4. – Harrison Pickett May 04 '15 at 18:50
  • Another possibility is that something has removed your file, but your script is still holding it open. The space should be reclaimed if you reboot. – lcd047 May 04 '15 at 19:37
  • If the file got renamed to have a period as the first character it won't show up in an normal ls command. Try ls -a. Using du on the containing directory may show your file as well. – BillThor May 05 '15 at 02:23
  • But, like I said... it isn't just one file. It's an entire directory that vanished... containing several source files one smallish data file and one, what should be, huge data file. But /only/ that directory vanished. That's what I can't explain. – Harrison Pickett May 05 '15 at 03:19

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