[nSLUG] Multiply-claimed blocks?
nslug at fop.ns.ca
Wed Aug 31 14:12:54 ADT 2011
On Wed, 31 Aug 2011, Mike Spencer wrote:
> Ben Armstrong <synrg at sanctuary.nslug.ns.ca> wrote:
>> However, cosmic rays are well known to cause bit flipping in RAM,...
> 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 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...."
No reason a magnetic bit on a hard drive can't be flipped as well as a bit
in a RAM chip. Drives also do a pretty good job of dying on their own -
is a slightly depressing paper on failure rates of hard drives in a large
scale environment. I also vaguely recall hearing about a prof who ran a
daily md5 of all the files in his ~, and regularly found checksum errors.
>> Keep a live system around for just such an occasion, e.g.
> That Debian disk sounds like a good thing. The fly in the ointment
> would be that the packages it holds for re-installing corrupted bits
> would be configured for Debian. I have no idea what problems, if any,
> I might encounter in that account. I wonder if someone has made a
> similar CD/DVD for Slack. I shall have to look around.
Boot the Debian rescue disk (or any that take your fancy - I find Recovery
Is Possible has a nice choice of tools), fix the disk, mount it on /mnt,
then chroot /mnt and you are back in your Slackware environment to finish
repairs. Exit out if you need to get back to the host environment (or
More information about the nSLUG