[Bug-ddrescue] Question about "No space left on device" message

[Tom Williams]

I'm using ddrescue 1.17 on Ubuntu 14.10 Linux (64-bit) to copy data from
one external 2TB hard drive to another 2TB external hard drive.  Both
drives are connected to my system via USB ports.   I let ddrescue run
for 6 days before it finally stopped with the following message:

ddrescue: write error: No space left on device

Here is the command I issued:

address@hidden:~$ sudo ddrescue -r3 /dev/sdg /dev/sdh
ddrescue: Output file exists and is not a regular file.
ddrescue: Use '--force' if you really want to overwrite it, but be
          aware that all existing data in the output file will be lost.
Try 'ddrescue --help' for more information.
address@hidden:~$ sudo ddrescue -r3 /dev/sdg /dev/sdh --force


GNU ddrescue 1.17
Press Ctrl-C to interrupt
rescued:     1646 GB,  errsize:    354 GB,  current rate:     720 kB/s
   ipos:     2000 GB,   errors:    9726,    average rate:    4289 kB/s
   opos:     2000 GB,    time since last successful read:       0 s
Copying non-tried blocks...
ddrescue: write error: No space left on device
address@hidden:~$

/dev/sdg is the original hard drive and /dev/sdh is the new, empty hard
drive.   Both hard drives are 2TB in size:

Disk /dev/sdg: 1.8 TiB, 2000398934016 bytes, 3907029168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: F2423982-AD62-4A91-9305-7E8444C65BDB

Device      Start        End    Sectors  Size Type
/dev/sdg1      40     409639     409600  200M EFI System
/dev/sdg2  409640 3906766983 3906357344  1.8T Apple HFS/HFS+

GPT PMBR size mismatch (3906963448 != 3906963455) will be corrected by
w(rite).

Disk /dev/sdh: 1.8 TiB, 2000365289472 bytes, 3906963456 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: A58EACF6-DE44-43F8-9150-47FA3842849B

Device      Start        End    Sectors  Size Type
/dev/sdh1      40     409639     409600  200M EFI System
/dev/sdh2  409640 3906701271 3906291632  1.8T Apple HFS/HFS+

The new hard drive, /dev/sdh, is a Western Digital "My Passport for Mac"
2TB external hard drive.

I did some web searches on the "write error: No space left on device"
message I received and didn't find anything relating to what I'm
experiencing. I did find some discussion about the logfile encountering
a space issue, but I'm not using a logfile (no particular reason why I
didn't).


When I try to mount the new drive, it doesn't mount and I get these
errors in dmesg output:

[406070.521186] hfsplus: invalid secondary volume header
[406070.521193] hfsplus: unable to find HFS+ superblock
[406080.059713] hfsplus: invalid secondary volume header
[406080.059719] hfsplus: unable to find HFS+ superblock

Now, while ddrescue was running, periodically I would hear loud
clicking, more like "clacking," sounds from the original hard drive. 
Apparently, the drive was dropped and the owner was concerned about
losing photos.  That's why I suggested getting the data off the original
hard drive NOW, while the data is still accessible.

Any ideas why I received the "write error:  Np space left on device"
message when both drives are the same size, 2TB?

Thanks!

Peace...

Tom

-- 
/When we dance, you have a way with me,
Stay with me... Sway with me.../