[NCLUG] Hard disk failure

[Matt Clauson]

dobbster wrote:

>> >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...

     -n     causes mke2fs to not actually create a  filesystem,
              but display what it would do if it were to create a
              filesystem.

basically, adding the -n flag causes mk*fs to perform a 'dry run' and tell 
you what it would do, without doing it.  -S and -n are VERY different flags.

>> >  I get the same results using other superblocks besides 32768. 
>> >  Shouldn't
>> > there
>> >  be superblocks prior to that?

> This is a Mandrake 7.1 system.  I'm not sure what the bytes/inode is.

Without doing a test install, I couldn't say either.

>> >  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.)

Unless I post an explanation of how a filesystem works, but I think it 
might be a good crowd draw for the next meeting.  (Tummy.com folks:  Are we 
meeting at any new offices you may have acquired yet, or should I put this 
presentation on the back burner for now?)

On the other hand, I might just get off my lazy ass tonight and post how a 
filesystem works...

> It's 2.2.15.

Hmm, not kernel cruft, then.  Did you install/change anything major on your 
Linux box in/around the same time?  It seems VERY odd that a piece of Win 
software other than the OS would demolish a Unix filesystem this badly...

>> 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?

Yeah, no problem.

--mec