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Re: udev memory problem when trying to plug a disk with corrupted partition table

Le 20.11.2014 22:26, Scott Ferguson a écrit :
On 21/11/14 06:45, Pascal Hambourg wrote:
Scott Ferguson a écrit :

Might be worth fscking the disk first in case that's where the problem lies.

Why ? fsck works on filesystems, not disks or partition tables.

Good question - because I didn't spend much time thinking about it, or, because I haven't used ms-dos partition tables for a very long time? :/

Regardless - maybe badblocks would be a better way of checking if the
problem is a result of damage to where the E(P)BRs are written?
Certainly simpler than examining the E(P)BRs for errors which would be
my next course of action if I had no backups of the disk.

(I suspect) There are at least two possible scenarios(?) which would
result in a problem that the OP is experiencing[*1]:-
;the OP accidentally overwrote an EBR i.e. created another extended
partition at some later point (1st sector of the extended partition?)
;a damaged sector containing an EBR

In the first case parted rescue may/should be able to fix the problem.

The OP could probably get more info by checking the E(P)BRs. The problem
'might' be in the first or last E(P)BR (again, I 'suspect' Martin is
right about the looping)
Perhaps (from unreliable memory):-
dd if=/dev/sdc bs=512 count=1 skip=22026238 | hexdump -C
likewise with the last extended partition, and then the same on the
E(P)BRs 'might' show the error?

I note that's a lot of suspicions, mights, and guesses - but again, I
welcome input and correction.

[*1] I'm guessing, and welcome input - as I suspect would the OP

An interesting problem, sadly the person most likely to know the answer
hasn't been seen on the lists for some time.

Kind regards

First, sorry for delay and thanks for replies. I won't have time to fix this for now, I will try to find time ASAP. Not that I really mind the data which were on that disk, but it will allow me to tinker with partition tables and such things on which I do not have a good knowledge. I had even no idea that logical partitions were a chained list, but now that you say it, it makes sense.

Also, what is EBR (or EPBR, which seems to be some sort of enhanced whatever may be a EBR)? To fix things, I tried to take a look at testdisk, which was able to find partitions. Lot of them, in facts, included lot of... removed partitions (I did a lot of experiments on that disk before). Plus, I have no idea about how to ask it (testdisk) to fix, apply things? Any document about how to use it? Not the man, I already have read it, and it's plain useless.

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