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Date:      Fri, 23 Feb 2007 11:08:29 -0500
From:      "Marty Landman" <martster@gmail.com>
To:        "Ian Smith" <smithi@nimnet.asn.au>
Cc:        freebsd-questions@freebsd.org
Subject:   Re: input/output error on hd
Message-ID:  <70063950702230808h433f61cscfd1abe43b578292@mail.gmail.com>
In-Reply-To: <Pine.BSF.3.96.1070223171809.25339A-100000@gaia.nimnet.asn.au>
References:  <20070223054641.12DD316A41B@hub.freebsd.org> <Pine.BSF.3.96.1070223171809.25339A-100000@gaia.nimnet.asn.au>

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On 2/23/07, Ian Smith <smithi@nimnet.asn.au> wrote:

So just show 'fdisk ad1' to see the disk's partition (slice) table (which
> may be damaged, but it's the only one you're interested in).


%sudo fdisk ad1
******* Working on device /dev/ad1 *******
parameters extracted from in-core disklabel are:
cylinders=486344 heads=16 sectors/track=63 (1008 blks/cyl)

Figures below won't work with BIOS for partitions not in cyl 1
parameters to be used for BIOS calculations are:
cylinders=486344 heads=16 sectors/track=63 (1008 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:
sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD)
    start 63, size 490223412 (239366 Meg), flag 80 (active)
        beg: cyl 0/ head 1/ sector 1;
        end: cyl 1023/ head 254/ sector 63
The data for partition 2 is:
<UNUSED>
The data for partition 3 is:
<UNUSED>
The data for partition 4 is:
<UNUSED>
%


If 'fdisk ad1' isn't showing any sensible data for 'partition 1' (ad1s1)
> then your boot sector is hosed.


Does the above result mean that my boot sector is ok?

> %sudo fsck /dev/ad1cs1
> > fsck: Could not determine filesystem type
> > %sudo fsck /dev/ad1c
> > fsck: exec fsck_unused for /dev/ad1c in /sbin:/usr/sbin: No such file or
> > directory
>
> You shouldn't be doing any of this with the 'c' partition, which is meant
> to cover the whole disk, but doesn't describe any of its slices.


Unfortunately I had incorrectly been using ad1s1c for this disk, is there
anything I can do about it now? Would that help with the effort to recover
the data?

I gather you think your data should be on ad1s1.  Does 'bsdlabel ad1s1' say
> anything sensible?


 %sudo bsdlabel ad1s1
# /dev/ad1s1:
8 partitions:
#        size   offset    fstype   [fsize bsize bps/cpg]
  c: 490223412        0    unused        0     0         # "raw" part, don't
edit
%

If not, does bsdlabel ad1s2, ad1s3 or ad1s4, if fdisk ad1 shows anything in
> s2, s3 or s4.


s2-4 all show "No such file or directory" for bsdlabel

As you mentioned elsewhere, you appear to have a bunch of bad blocks early
> on this disk.


Yes, based on working with the dd cmd on /dev/ad1s1 and playing with the
skip parm have found that blocks 129-144 give input/output errors. Does this
indicate a hardware error necessarily? This problem came about as the result
of a power outage; might there "just" be hosed data on those sectors?

Have you a spare drive you can dd this one to, in its current state?


No, it's a 250GB drive, the largest on my LAN. Would have to buy a
replacement drive and then dd to that. If it came to that, while a backup hd
might be a good idea, I'd possibly just live with recreating the data
instead.

What does 'ls -l /dev/ad1*' have to say?


%ls -al /dev/ad1*
crw-r-----  1 root  operator    0,  70 Feb 22 17:56 /dev/ad1
crw-r-----  1 root  operator    0,  74 Feb 22 17:56 /dev/ad1a
crw-r-----  1 root  operator    0,  75 Feb 22 17:56 /dev/ad1c
crw-r-----  1 root  operator    0,  82 Feb 22 17:56 /dev/ad1cs1
crw-r-----  1 root  operator    0,  94 Feb 22 17:56 /dev/ad1cs1c
crw-r-----  1 root  operator    0,  73 Feb 22 17:56 /dev/ad1s1
crw-r-----  1 root  operator    0,  84 Feb 22 17:56 /dev/ad1s1c


> And please don't top-post ..


Sorry about that Ian, appreciate your help.

Marty

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