[Bug-ddrescue] image copy much smaller than disk size?

[Patrick Wambacq]

Hi,

I am a newbie to ddrescue, so forgive my ignorance if my questions have a
simple and obvious answer.

My daughter's PowerBook has a crashed disk and I tried ddrescue to copy
whatever is possible. I took the disk out of the laptop and attached it to a
usb-to-ide converter. I am using ddrescue 1.12 on my MacBookPro and tried to
copy the 100GB disk to a disk image on a large (500GB) external disk. I
stopped diskarbitrationd on my mac to prevent os-x from mounting the
inserted defective disk (see 
http://forum.soft32.com/mac/prevent-automounting-ftopict113266.html
http://forum.soft32.com/mac/prevent-automounting-ftopict113266.html ) and
entered

sudo ddrescue -v /dev/disk3 /Volumes/bigdisk/image.dmg
/Volumes/bigdisk/image.log

and ddrescue started working - cool!
Then some disk I/O errors appeared - I repeatedly disconnected the disk,
stopped ddrescue and started over again a few blocks further. After reaching
the end of the disk, I started again with

sudo ddrescue -v -R -s(some_size) etc

and adjusted (some_size) when I had to restart due to I/O errors or the disk
simply stopping to respond, all this in order to decrease the total error
size.

Now my questions:
- is what I am doing (aborting and restarting) the right thing when I/O
errors appear or when the disk stops working?
- every time when I abort (disconnect the disk, interrupt ddrescue), I had
to restart my mac (even reset: simple shutdown hangs) because interrupting
ddrescue leaves me with a running process (no matter how long I wait) and
restarting ddrescue simply does nothing. Can this be avoided?
- I noticed that the image size is around 420M when looking at it with ls
-l, and it does not change any more. This is very small compared to what I
expect (100G). On the other hand, when looking at it with the Finder,
sometimes size is 90-something GB, and sometimes also 420M. What's going on
here? I stopped working on the disk because I am afraid that what I am doing
is useless.

Thanks

Patrick
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