Re: Recovering filesystem with large number of orphaned inodes?

[Andy Ruhl <acruhl%gmail.com@localhost>]

On Mon, Apr 14, 2014 at 7:34 PM, John D. Baker 
<jdbaker%mylinuxisp.com@localhost> wrote:
> I had occasion to deal with a system whose hardware RAID-5 had lost a
> component and operated in degraded mode for some time.  Following a
> power failure, the machine (a DELL PowerEdge 2550, IIRC) refused to boot
> from the degraded, but operational RAID.
>
> The failed component was replaced and the RAID card's firmware utility
> was used to reconstruct the logical volume.  The machine then proceeded
> to boot, but the filesystem check revealed very damaged filesystems.
>
> Fortunately, the owner of the system had practiced good separation of
> infrastructure vs application.  I ultimately declared the OS filesystems
> a total loss and installed a fresh 6.1_STABLE from sometime in the
> middle of 2013 (and recently updated, then updated to i386-6.99.40).
>
> The remaining filesystem is where the user's data resides.  From my
> previous attempts at salvaging the OS filesystems, I can expect more
> orphaned files than can be referenced in a single "lost+found" directory.
>
> From a brief perusal of "fsck_ffs" sourcecode, it appears that if the
> "linkup()" routine returns 0 (zero) for any reason, the inode being
> processed is simply cleared.
>
> I'd like to give the best possible chance to recover data but I don't
> really feel like having to approve 65534 reconnections.  I'd like to use
> the "-y" option, but have fsck exit if it can't attach the orphan file.
> Then I can move the "lost+found" directory out of the way and start over
> with a new one.
>
> That seem reasonable?

Sorry to go off topic a bit.

What is your goal? To recover newer stuff than the owner was able to
get back? In this case you probably need to go through every inode I
guess. What's it worth? At some point it becomes harder than the data
is worth... You probably know that.

I assume when you say "routine returns 0" means it can't link the
inode and it just removes it? Sorry, I didn't look at the code...

If you're not using -y, I guess you would have to script your way
through using -n and moving the bad stuff out of the way every time
you hit it, unless you have a better idea. I'd like to hear it.

Andy