[mythtv-users] Is my JFS broken ?

Graham Wood mythtv-users at spam.dragonhold.org
Wed Aug 20 19:44:26 UTC 2008

On Wed, Aug 20, 2008 at 06:19:35PM +0200, r2d2 wrote:
> > Almost definitely a hardware error on the disk.
> Bad news.
Yeah - I've had a couple of disks die on me recently (at work), and despite instructions 
otherwise the users had put "important" data onto local unmirrored disks.  ddrescue managed 
to recover about 95% of the disk for me, but you can probably guess where the data they 
wanted was....

> I didn't notice anything about IO errors or other errors. As I mentioned,
> there was "Corrupt dmap page" in /var/log/messages before the filesystem was
> first damaged.
Those would certainly have caused the corruption, but in theory once the fsck was complete, 
it should be "ok" again.  If you reboot and then try and create that 10M file without doing 
anything else first, does that bomb out still?

> I will consider  buying a new disk. It would be quite difficult to identify
> the broken bits as the filesystem resides on a logical volume built over 2
> software RAID arrays (raid1, 2 disks and raid5, 4 disks). I know this is an
> awful mess. TV shows and movies are not so important, but I am disappointed
> : the RAID was inefficient to prevent this kind of problem.
That (and the lack of errors) implies that it's not actually a hardware problem.

The zero byte file is going to be an entry in an existing inode (or equivalent for jfs), and 
the file with contents is going to require the allocation of new space for the contents.  

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