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Help for ddrescue and an old SCSI Disk
Authored by: macintact on Apr 08, '10 02:51:35AM

Hello everybody,

although it's quite long ago, and if this post is still alive, I want to ask for your help on my specific problem:

1st of all I have to admit that I don't have any clue to Unix commands or working with the Terminal in OS X. All of what I typed in the Terminal was found on the Internet and then trial and error.

The specific problem was to get data of an old 40 MB SCSI HD coming from an Mac Classic. As I didn't have any real working SCSI Mac, I did the following:

Got an old SCSI Disk enclosure, got an old Orange Micro SCSI to FireWire adapter, connect it to my lovely Cube, installed all the SW I could find and spend ages in finding out how to mount that dead thing. Well, at some point it worked out and I came to this:

Last login: Mon Mar 29 18:31:40 on ttyp2
Welcome to Darwin!
Cube:~ cube$ system_profiler SPFireWireDataType

FireWire Bus:

Maximum Speed: Up to 400 Mb/sec


Manufacturer: CONNER
Model: 0x1
GUID: 0xD01600000047BE
Maximum Speed: Up to 200 Mb/sec
Connection Speed: Up to 200 Mb/sec
CP3040A-40mb-3.52.31 Unit:
Unit Software Version: 0x10483
Unit Spec ID: 0x609E
Firmware Revision: 0x120
Product Revision Level: 2.31
CP3040A-40mb-3.52.31 SBP-LUN:

Cube:~ cube$ disktool -m system_profiler SPFireWireDataType
system_profiler device will attempt to be mounted ...
***Disk Appeared ('disk0',Mountpoint = '', fsType = '', volName = '')
***Disk Appeared ('disk0s1',Mountpoint = '', fsType = '', volName = '')
***Disk Appeared ('disk0s2',Mountpoint = '', fsType = '', volName = '')
***Disk Appeared ('disk0s3',Mountpoint = '', fsType = '', volName = '')
***Disk Appeared ('disk0s4',Mountpoint = '', fsType = '', volName = '')
***Disk Appeared ('disk0s5',Mountpoint = '', fsType = '', volName = '')
***Disk Appeared ('disk0s6',Mountpoint = '', fsType = '', volName = '')
***Disk Appeared ('disk0s7',Mountpoint = '', fsType = '', volName = '')
***Disk Appeared ('disk0s8',Mountpoint = '', fsType = '', volName = '')
***Disk Appeared ('disk0s10',Mountpoint = '/', fsType = 'hfs', volName = 'Macintosh HD')
***Notifications Complete for type 1
***Disk Appeared ('disk1',Mountpoint = '', fsType = '', volName = '')
***Notifications Complete for type 1


Last login: Mon Mar 29 18:32:32 on ttyp1
Welcome to Darwin!
Cube:~ cube$ ddrescue -v /dev/disk1 MyVolImage.dmg MyVolRescue.log

About to copy 9223 PBytes from /dev/disk1 to MyVolImage.dmg
Starting positions: infile = 0 B, outfile = 0 B
Copy block size: 128 hard blocks
Hard block size: 512 bytes
Max_retries: 0
Direct: no Sparse: no Split: yes Truncate: no

Press Ctrl-C to interrupt
Initial status (read from logfile)
rescued: 0 B, errsize: 0 B, errors: 0
Current status
rescued: 0 B, errsize: 4294 MB, current rate: 0 B/s
ipos: 1534 kB, errors: 1, average rate: 0 B/s
opos: 1534 kB, time from last successful read: 2.6 d
Splitting failed blocks...


As you can see it was working now over for some days! But after the third day it seemed to start all over again.In the night I saw at " ipos:" over 97200000 kB (or something like that). I the "fs_usage" Terminal-window I seem to have lost all the old notes, and only have this now (I shortened it a lot!):

fs_usage: buffer overrun, events generated too quickly
06:36:13 RdMeta 450.067500 W ddrescue
06:36:13 access /dev/disk1 0.000168 ddrescue
06:36:13 fsync 0.000024 ddrescue
06:36:13 open MyVolRescue.log 0.003194 W ddrescue
06:36:13 fstat 0.000018 ddrescue
06:36:13 write 0.000187 ddrescue
06:36:13 close 0.000035 ddrescue
06:36:13 write 0.000043 ddrescue
06:36:13 write 0.000037 ddrescue
06:36:13 write 0.000032 ddrescue
06:36:13 write 0.000034 ddrescue
06:36:13 lseek 0.000012 ddrescue
fs_usage: buffer overrun, events generated too quickly
06:40:43 RdMeta 270.010096 W ddrescue
06:40:43 access /dev/disk1 0.000181 ddrescue
06:40:43 fsync 0.000027 ddrescue
06:40:43 open MyVolRescue.log 0.002749 W ddrescue
06:40:43 fstat 0.000016 ddrescue
06:40:43 write 0.000188 ddrescue
06:40:43 close 0.000035 ddrescue
06:40:43 write 0.000044 ddrescue
06:40:43 write 0.000035 ddrescue
06:40:43 write 0.000030 ddrescue
06:40:43 write 0.000028 ddrescue
06:40:43 lseek 0.000012 ddrescue
fs_usage: buffer overrun, events generated too quickly
06:41:13 RdMeta[async] 300.010836 W ddrescue
fs_usage: buffer overrun, events generated too quickly

The "fs_usage: buffer overrun, events generated too quickly" is coming permanently in a way and I don't really know what that means. The other things is that the DMG-File is only 8k big (and I can't mount it in the Finder), and the ddresuce log says this now:

# Rescue Logfile. Created by GNU ddrescue version 1.11
# current_pos current_status
0x0017C000 /
# pos size status
0x00000000 0x00040A00 -
0x00040A00 0x00017C00 /
0x00058600 0x00020400 -
0x00078A00 0x0003BE00 /
0x000B4800 0x00040400 -
0x000F4C00 0x0007DE00 /
0x00172A00 0x00009800 -
0x0017C200 0x00074600 /
0x001F0800 0x00000400 -
0x001F0C00 0x001FFE00 /
0x003F0A00 0x00000400 -
0x003F0E00 0x003FFE00 /
0x007F0C00 0x00000400 -
0x007F1000 0x007FFE00 /
0x00FF0E00 0x00000400 -
0x00FF1200 0x00FFFE00 /
0x01FF1000 0x00000400 -
0x01FF1400 0x01FFFE00 /
0x03FF1200 0x00000400 -
0x03FF1600 0x03FFFE00 /
0x07FF1400 0x00000400 -
0x07FF1800 0x07FFFE00 /
0x0FFF1600 0x00000400 -
0x0FFF1A00 0x0FFFFE00 /
0x1FFF1800 0x00000400 -
0x1FFF1C00 0x1FFFFE00 /
0x3FFF1A00 0x00000400 -
0x3FFF1E00 0x3FFFFE00 /
0x7FFF1C00 0x00000400 -
0x7FFF2000 0x7FFFFE00 /
0xFFFF1E00 0x00000200 -

Can somebody explain some of that stuff to me? Is it just a waste of time, because that dmg file is useless? I already contacted Antonio Diaz and he send me the link to this post. He said that I have to tell ddrescue the size of the disc with this command:

ddrescue -v -s40MiB /dev/disk1 MyVolImage.dmg MyVolRescue.log

After that I gave up for now and stopped the rescue yesterday - and I haven't tried this command. But I'm still willing to try my best with some help of yours!

Thanks for your time of reading this and hopefully you can help me with it!

Best regards,


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