[NCLUG] Hard disk failure
dobbster
dobbster at dobbster.com
Sun May 20 22:25:33 MDT 2001
> >From the mke2fs man page:
>
> -S Write superblock and group descriptors only. This
> is useful if all of the superblock and backup
> superblocks are corrupted, and a last-ditch recov
> ery method is desired. It causes mke2fs to reini
> tialize the superblock and group descriptors, while
> not touching the inode table and the block and
> inode bitmaps. The e2fsck program should be run
> immediately after this option is used, and there is
> no guarantee that any data will be salvageable.
>
> Short version: You can try and rebuild your superblock and group descriptors
> table using this flag, and not touch the inodes/inode tables. Note that this
> IS a method of last resort, and you DO run the risk of fux0ring the data
> completely... However, if nothing else works, it's worth a shot.
Ok... You mentioned -n (-N?) before, but when looking at the man page, I
couldn't find anything similar. -S clearly isn't quite the same, but at least
it (hopefully) leaves the data there...
> > I get the same results using other superblocks besides 32768. Shouldn't
> > there
> > be superblocks prior to that?
>
> Depends on the flags that your filesystem was created with -- with a default
> installation of a recent version of Debian (unstable, in fact!) that is not
> the case -- it builds with 4096 bytes per inode, and 8192 inodes per inode
> group. Unless you know some more statistics about the filesystem and/or have
> the flags that the filesystem was initially created with, I can't tell you.
> However, if you're running recent RH or derivatives (KRUD, SuSE, Mandrake,
> etc) or most any other modern distro, you most likely had no choice in how
> the filesystems were created, so I can only guess.
This is a Mandrake 7.1 system. I'm not sure what the bytes/inode is.
> > It seems weird that installing some Windows software could cause all of
> > this
> > damage. I don't even know what an "illegal triply indirect block" is.
>
> Make the next NCLUG meeting. If we're available with lecture space there,
> I'll do a presentation on how filesystems work. Otherwise, I'll post again
> shortly on it. I learned this stuff in my Sun class last week, actually --
> interesting material.
Alas, now I am committed to leave my dungeon and be semi-sociable at an NCLUG
meeting. :-) I'll plan on attending (6/5, I assume.)
> Another thing that just hit my mind: did your operating kernel rev change to
> a pre-2.2 kernel? There are some modes of the ext2 filesystem that won't
> work with those older kernels... And I just realized it. If you're running
> an ancient ass kernel for some reason, that might explain it. Hmm. Check
> your bootup messages and let us know.
It's 2.2.15.
> Is there some time next weekend that we could meet somewhere (my place/office
> or yours) and I could take a gander at the system? This actually poses an
> interesting problem, and I'd love to see it through.
Sure; if you like, I can leave the machine alone until then. There's no big
rush. Scheduling a time might be challenging for me. Can we maybe get in
contact sometime later in the week?
Thanks again...
Mark (dobbster at dobbster.com)
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