[DragonFlyBSD - Bug #2287] HAMMER(ROOT) Illegal UNDO TAIL signature at 300000001967c000

[YONETANI Tomokazu via Redmine]

Issue #2287 has been updated by YONETANI Tomokazu.


Hi,

I've recovered from this situation by writing a modified version
of hammer utility to fill up the rest of the UNDO FIFO with DUMMY
records.

But in practice we need a read-only-without-recovery option
in hammer_mount (it still runs recover_stage1 and it failed for me),
so as to determine that the filesystem without processing UNDO record
will be usable.

Best Regards,
YONETANI Tomokazu.

On Thu, Feb 09, 2012 at 12:35:24AM +0900, YONETANI Tomokazu wrote:
> Hi.  I tried `hammer show-undo'.  It found a zero-sized field at
> 300000001967c000, and subsequent entries look like that
> until I pressed ctrl+c.
> 
> Volume header UNDO 3000000019679708-300000001967aea8/3000000040000000
> Undo map is 1024MB
> 3000000000000000 UNDO(0200) seq=33366e05 dataoff=2000003e69742938 bytes=472
> 3000000000000200 UNDO(0200) seq=33366e06 dataoff=2000003e69742b10 bytes=472
> 				:
> 300000001967bc00 UNDO(0200) seq=3364b571 dataoff=2000003eb86d4c40 bytes=472
> 300000001967be00 UNDO(0200) seq=3364b572 dataoff=2000003eb86d4e18 bytes=472
> 300000001967c000 UNKNOWN(0000,0000) seq=00000000
> Illegal size field, skipping to next boundary
> 300000001967c000 UNKNOWN(0000,0000) seq=00000000
> Illegal size field, skipping to next boundary
> 				:
> 
> Maybe format_undomap() can fix (reset) this truncated UNDO map?
> 
> Best Regards,
> YONETANI Tomokazu.
----------------------------------------
Bug #2287: HAMMER(ROOT) Illegal UNDO TAIL signature at 300000001967c000
http://bugs.dragonflybsd.org/issues/2287

Author: YONETANI Tomokazu
Status: New
Priority: Normal
Assignee: 
Category: 
Target version: 


Hello.

After having experienced a few panics, the root filesystem is
no longer able to be mounted, even in read-only mode:

(booted from a USB stick)
# mount -thammer -o ro /dev/da0s1d /mnt
HAMMER(ROOT) recovery check seqno=3364b54c
HAMMER(ROOT) Illegal UNDO TAIL signature at 300000001967c000
HAMMER(ROOT) recovery failure during seqno fwdscan
HAMMER(ROOT) recovery complete
Failed to recover HAMMER filesystem on mount
hammer: mount  on /mnt: Input/output error

I haven't tried `hammer recover' yet, as I have no idea what it does.
Is there anything I can do to recover from this situation?  This is
a machine dedicated to testing DragonFly stability, so I can install
from scratch in the worst case.
 
The error message looks similar to the one described in issue1984,
but in this case even R/O mount fails.

The current kernel is built from 4f459, and it occasionally panics
even under almost no CPU or disk load.  It could be a hardware failure,
but I couldn't find any indication of it as far as I watched the console
while it booted with the USB stick.
The previous kernel was built from 190f1b64, and it survived 10 days
without panic under pbulk load.

Best Regards,
YONETANI Tomokazu.


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