dscheck(#ar/2): negative b_blkno error on FreeBSD-4.10-STABLE

Vladimir Zhurov vzhurov at uwo.ca
Wed Jun 30 13:02:16 PDT 2004


Thank you for reply.

As file system problems started to pile up I have decided to re-format 
and restore from backups. I have tested all four HDD's in array using WD 
diagnostic utility and extended test did not find any problems.
So I attempted to re-initialize array using the following method from 
the handbook (section 13.3.2.2 from "Adding disks" section (with 
modifications at newfs stage)):

# dd if=/dev/zero of=/dev/ar0 count=2
# disklabel /dev/ar0 | disklabel -BrR ar0 /dev/stdin
# newfs -U /dev/ar0c

However, if I would run fsck /dev/ar0c it would immediately report 
hundreds of partially allocated inodes.

fdisk ar0 reports the following:

******* Working on device /dev/ar0 *******
parameters extracted from in-core disklabel are:
cylinders=19452 heads=255 sectors/track=63 (16065 blks/cyl)

Figures below won't work with BIOS for partitions not in cyl 1
parameters to be used for BIOS calculations are:
cylinders=19452 heads=255 sectors/track=63 (16065 blks/cyl)

Media sector size is 512
Warning: BIOS sector numbering starts with sector 1
Information from DOS bootblock is:
The data for partition 1 is:
<UNUSED>
The data for partition 2 is:
<UNUSED>
The data for partition 3 is:
<UNUSED>
The data for partition 4 is:
sysid 165,(FreeBSD/NetBSD/386BSD)
     start 0, size 50000 (24 Meg), flag 80 (active)
	beg: cyl 0/ head 0/ sector 1;
	end: cyl 1023/ head 255/ sector 63

Is it controller/cable/some other hardware problem or is it software 
related and I am just doing something wrong?

Vlad.

>>dmesg.today:
>>dscheck(#ar/2): negative b_blkno -1721888480
>>
>>messages:
>>/kernel: dscheck(#ar/2): negative b_blkno -1721888480
> 
> 
> I've seen this if the array or partition table is corrupted. The check is
> at the front of dscheck() in src/sys/kern/subr_diskslice.c.  You might
> make sure your raid array is functioning normally and the fdisk table
> hasn't been spammed.
> 
> 
>>Does anyone know what is the reason for such error and whether it is
>>critical?
> 
> 
> It shouldn't happen -- you might go exploring with fdisk(8).



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