[nSLUG] Multiply-claimed blocks?

Ben Armstrong synrg at sanctuary.nslug.ns.ca
Wed Aug 31 12:55:21 ADT 2011


On 08/31/2011 01:55 AM, Mike Spencer wrote:
> I'd heard that, of course. In this case, the corruption seems to have
> been in a lib file on HD that (AFAIK) is written at install time and never
> re-written unless upgrading or the like.

I'm not sure exactly how this happens, but I've had lib files corrupted,
too. Presumably when upgrading.

> I had not heard that cosmic
> rays (energetic neutrons according to the article you cited) could flip
> a bit on a HD.  But, as you say, "Anything is possible...."

Well, what I meant is that cosmic rays could corrupt buffers in RAM.
Once they are flushed to disk, the bit flip is preserved on the drive.

> Soon after got my first computer, I got a take-home job to translate a
> game from BASIC into C. I had spent many hours with 132 col printouts,
> colored markers etc. tracing the logic of the BASIC and keeping track
> of it all with a spreadsheet on a 5.25 floppy.  And, of course, just
> as I was about ready to start writing C code, the floppy was
> corrupted. So my first run at writing a "real" C program switched from
> the game to writing a low level utility to recover every bit of
> uncorrupted data from a floppy.  It was entertaining, so much so that
> I never got back to the guy's game.  Ah, but things were easier with
> CP/M. :-)

Ah, the bad old days of floppies. If I had a nickel for every bad image
write of a Debian install floppy ...

> I have (and just used for this) the Slackware distro DVD. 
> It boots into a working system with (AIUI) everything on a
> ramdisk and leaves the real HD alone until you mount or fsck it. But
> it lacks many of the tools that I use all the time.  more instead of
> less, vi instead of emacs [1], console only and no working support for
> USB or LAN.

Which is why you need to use live-build and make a custom rescue image
with *exactly* the stuff you want on it! Does slack have anything like this?

Ben



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