[PLUG] Busted computer

Bill Barry bill at billbarry.org
Wed Oct 17 05:47:34 UTC 2007


On 10/16/07, John Jason Jordan <johnxj at comcast.net> wrote:
>
> This time it seems to be a bad superblock. Googling on "superblock"
> yields a lot, but the more I google the confuseder I get. Here is what
> led up to the problem:
>
> A couple days ago at PSU the computer would not boot. The error message
> seemed to have something to do with being unable to find the Realtek
> ethernet port. I carry a phillips head screwdriver with me, and I used
> it to disassemble the part of the case over the ethernet plug. Then I
> tapped on it a lot, loosened and tightened the screws holding the
> housing over it, and reassembled it. It booted normally. But later at
> home it exhibited the same symptoms. I got it to boot just by banging
> it lightly on the corner where the ethernet plug is located. Since then
> I have rebooted half a dozen times without incident.
>
> Today, upon returning home from PSU, I got
>
> Grub loading 1.5
> Please wait
> Error 2
>
> All the usual disassembly/banging on things/reassembly failed to remedy
> the problem. "Error 2" appears to be a Grub error that means (loosely
> translated) "dude, sumpin' bad happened to your filesystem." Further
> googling and trying various things at the command line after booting to
> a Gutsy Release Candidate live CD reveals that evidently I have a bad
> superblock on /dev/hda2.
>
> Aside: Although they are scattered all over the place and would be a
> PITA to reassemble, I have backup copies of everything on /dev/hda2
> that would be bad to lose, except a couple of recent documents and the
> last couple of weeks worth of financial data in Quickbooks (restorable
> from paper copies).
>
> Aside 2: On the outside of the case this appears to be a Compaq R3240
> laptop. In reality is is a rebadged Piece-O-Shit (tm) laptop assembled
> from parts supplied by the lowest bidder by lead-poisoned Chinese
> laborers. And yes, I have begun shopping for its replacement.
>
> Returning to the topic at hand, at
>
>
> http://www.cyberciti.biz/tips/understanding-unixlinux-filesystem-superblock.html
>
> I gathered that Linux keeps copies of the superblock data which you can
> get with "dumpe2fs /dev/hda3 | grep -i superblock." Unfortunately, that
> doesn't work on a filesystem that cannot be mounted (already tried
> that). The site also suggests "e2fsck -f /dev/hda2," but that also
> fails if the superblock can't be read. Finally, the site suggests "sudo
> e2fsck -f /dev/hda2" to get the data. This resulted in:
>
> Block size = 4896 (log=2)
> 7325696 inodes, 14651288 blocks
> 732564 blocks 5.88% reserved for the super user
> First data block = 0
> Maximum filesystem blocks = 4294967296
> 448 block groups
> 32768 blocs per group, 32768 fragments per group
> 16352 inodes per group
> Superblock backups stored on blocks:
>    32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632,
> 2654208, 4896000, 7962624, 11239424
>
> And evidently I can repair the superblock with a command like "e2fsck
> -f -b 8193 /dev/hda2," except the site let me down by failing to tell
> me what the "8193" or the -f and -b mean. I am guessing that the "8193"
> should be one of the numbers of where the superblock backups are stored
> above, and that any of them will do.
>
> I am about to run:
>
> e2fsck -f -b 32768 /dev/hda2
>
> But before I do it and end up destroying western civilization, I
> thought I might ask here first to see if my thinking is correct.
>

Might work, I would install testdisk. There is a deb package so I assume
there is an ubuntu one also.I remember it being able to repair this
superblock problem. On the other hand western civilization does not have
much left so go ahead, destroy what is left.

Bill



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