Reading bad disk

[Lars Hecking <lhecking%nmrc.ie@localhost>]

 Hi all,

 I'm trying to save data from a broken disk - wondering whether it's possible
 at all.

 Setup: A3000, two internal disks, two external. Ext1 has NetBSD on it,
 ext2 OpenBSD. Both are Sun 1.05GB (Seagate) drives.

 The box was unused for over half a year, on account of the motherboard
 being in a different location :), waiting for the 2nd battery surgery,
 and also a new keyboard. In this period of inactivity, the disk with OBSD
 went bad - no idea how, might just be old age.

 My idea was whether I could salvage anything from that disk via NetBSD,
 but it seems to be next to impossible. Here's the relevant part of dmesg:


NetBSD 1.6.1 (RUSTY) #3: Mon Apr 28 00:59:53 IST 2003
    root@localhost:/usr/src/sys/arch/amiga/compile/RUSTY
Amiga 3000 (m68040 CPU/MMU/FPU)
total memory = 22528 KB
avail memory = 19312 KB
using 153 buffers containing 1224 KB of memory
memory segment 0 at 08000000 size 00600000
memory segment 1 at 07000000 size 01000000
memory segment 2 at 00000000 size 00200000
mainbus0 (root)
clock0 at mainbus0: CIA B system hz 100 hardware hz 709379
Calibrating delay loop... 111/1024 us
a34kbbc0 at mainbus0
ser0 at mainbus0: input fifo 512 output fifo 256
par0 at mainbus0
kbd0 at mainbus0: CIA A type Amiga
ms0 at mainbus0
grfcc0 at mainbus0
grf0 at grfcc0: width 640 height 400 colors 4
ite0 at grf0: rows 0 cols 0 repeat at (30/100)s next at (10/100)s has keyboard
fdc0 at mainbus0: dmabuf pa 0x1e525c: dmabuf ka 0x8b9f25c
fd0 at fdc0 unit 0: 3.5dd 80 cyl, 2 head, 11 sec [9 sec], 512 bytes/sec
ahsc0 at mainbus0
scsibus0 at ahsc0: 8 targets, 8 luns per target
aucc0 at mainbus0
audio0 at aucc0: half duplex
zbus0 at mainbus0: i/o size 0x00200000
grfcl0 at zbus0 pa 0x40000000 man/pro 2193/1
grf3 at grfcl0: width 640 height 480 colors 16
ite3 at grf3: rows 60 cols 80 repeat at (30/100)s next at (10/100)s has keyboard
grfcl: 2MB Spectrum being used
grfcl1 at zbus0 pa 0xe90000 man/pro 2193/2
ite at grfcl1:  not configured
scsibus0: waiting 2 seconds for devices to settle...
ahsc0: target 0 now synchronous, period=208ns, offset=12.
sd0 at scsibus0 target 0 lun 0: <IBM, DPES-31080, S31Q> SCSI2 0/direct fixed
sd0: 1034 MB, 4903 cyl, 4 head, 108 sec, 512 bytes/sect x 2118144 sectors
ahsc0: target 1 now synchronous, period=208ns, offset=12.
sd1 at scsibus0 target 1 lun 0: <IBM, DCAS-34330, S61A> SCSI2 0/direct fixed
sd1: 4134 MB, 8205 cyl, 6 head, 171 sec, 512 bytes/sect x 8467200 sectors
ahsc0: target 2 now synchronous, period=208ns, offset=12.
sd2 at scsibus0 target 2 lun 0: <SEAGATE, ST31200N SUN1.05, 8564> SCSI2 
0/direct fixed
sd2: 1006 MB, 2700 cyl, 9 head, 84 sec, 512 bytes/sect x 2061108 sectors
ahsc0: target 3 now synchronous, period=208ns, offset=12.
sd3 at scsibus0 target 3 lun 0: <SEAGATE, ST31200N SUN1.05, 8564> SCSI2 
0/direct fixed
sd3: 1006 MB, 2700 cyl, 9 head, 84 sec, 512 bytes/sect x 2061108 sectors
4 views configured
warning unknown dostype: 0x53575000 marking unused
warning found rdb->secpercyl(756) != rdb->nsectors(85) * rdb->nheads(9)
sd3(ahsc0:0:3:0):  Check Condition on CDB: 0x08 00 00 00 01 00
    SENSE KEY:  Media Error
     ASC/ASCQ:  Address Mark Not Found for ID Field
     FRU CODE:  0xe8
         SKSV:  Actual Retry Count: 0

sd3: rdb scan I/O error

 Does anybody have ideas what I could do? There is no critical data on the
 system, in fact, the configuration of the NetBSD disk is almost identical,
 give or take a few ports/packages. But it would be nice to salvage as much
 as possible.