recovery after power outage

Jerry McAllister jerrymc at
Wed Feb 7 15:43:13 UTC 2007

On Tue, Feb 06, 2007 at 09:06:05PM -0500, Marty Landman wrote:

> Jerry McAllister wrote:
> >Well, do as it says - choose a shell and run fsck manually.
> Heh, for starters I assumed (always a bad thing) that fsck wasn't available
> because I did a 'which fsck' and got 'which not found' as a response. But
> fsck itself is there.

Which is a built in shell command and you hadn't declared a shell yet.
But, fsck is run from a binary file and can be reached by specifying
the full path.

> >Just run /sbin/fsck /dev/ad1s1c.   Actually that would be a somewhat
> >unusual address - what they call a 'dangerously dedicated' disk.
> Can you explain or point me to more info on why that was a poor choice on my
> part? To explain more this is a 250 GB hard drive which is the primary slave
> and is mostly used as a data repository and shared via samba on my home
> office lan.

Mainly because it is non or less standard and some things may not
play nicely with it.   As long as it is used only in a FreeBSD
situation and there is never a problem with the disk, then it
will work fine.   But it is usually advisable to keep to the 
high road unless there is a reason not to.

> >But I think fsck should be able to work through it.
> snip
> >It the manual fscks don't work, then you may have to try some
> >extreme tactics to recover things on that partition or abandon
> snip
> >If you end up rebuilding the drive, then the next time make a
> >FreeBSD slice and then make a partition within that slice to
> >avoid that 'dangerously dedicated' config.
> I am not getting past this error with fsck. Get 16 lines saying:
> LBA=xxx
> for xxx in [191..206]
> then  a msg listing disk sectors that can't be read 128 through 143 and
> finally:
> /dev/ad1s1c: NOT LABELED AS A BSD FILE SYSTEM (unused)
> If I can recover the disk which has about 60GB's used out of 250GB and lose
> a few sectors it's really not a bad deal probably, but how do I go about
> trying at this point?
> Also it won't reboot now, although I've run fsck complete including on ads0.
> Do I have to edit /etc/fstab so ads1 isn't mounted to get a good boot?
> Unfortunately /usr isn't getting mounted and I have not editor available
> afaik.

Now you are getting beyond my experience.  I am thinking something
in the label got mushed or possibly the primary superblock got wacked.  
Sometimes the label can be rewritten, if the new one is identical to 
the old one, and then used to access the disk.  And, there are lots of 
spare superblocks written on the filesystem and it is possible to use
one as an alternate.  But I have never had to do either of these things, 
so someone else with experience there would be a better guide.


> Marty
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