[X4U] problem copying external HD to external HD

[David Ledger]

At 17:22 -0400 18/9/10, Doug Metzler wrote:
Thanks David
I'm doing a finder drag.  I'll try a terminal command next, didn't 
think of that.
Would that be cp -r  for a directory/folder?  Is there any other to try?
The data does incrementally appear on the WD drive until the point that the
internal drive is full.  Then I get a message that the internal drive is nearly
full followed a little later by a message that the operation can't be completed
because the startup drive is full.  I agree that "Copying data directly from
one external drive to another should have no effect on the internal drive
other than maybe some swap space for the copying process if you're
short on memory." which is why I'm confused.  It does look like there is some
virtual memory swapping going on with the internal drive usage 
varying a little bit
up and down (less then 1G) when other things are going on.  I can usually copy
over smaller folders, up to about 5G with no problem, and up to about 20G with
little problem.  But much larger than that it goes crazy.  Last night 
it filled the
entire 236G free space on the internal in the process of just trying 
to copy less
than 80G.

Doug

I generally don't use Finder drag for a large collection of files. 
Last year I did something similar to you and copied a tree of photos 
and iMovie projects onto a WD NAS drive with Finder drag. It seemed 
to save quite a bit of space, so I checked before deleting the 
originals. Lucky I did. Maybe 5% of the files hadn't been copied. I 
then copied the missing stuff in smaller chunks. Over several days of 
doing the next bit when I had a chance I did get it all copied. I 
also made a copy onto a 2TB USB drive so I could safely remove the 
originals. I've never  felt totally comfortable with Finder drag 
copy. What's it really doing when it's 'Preparing to copy'? Your 
problem may indicate that it copies to local disc first.

cp -R (rather than -r, there's a comment in the man page) at 10.5 and 
above should do a recursive copy including resource forks. Early 10.x 
didn't copy resource forks, and I think needed an option flag to do 
it in intermediate versions. Not sure where the breakpoints are.

Traditional mainstream Unix cp didn't used to have a -R option, so 
the usual way to copy a tree was
cd sourcefolder; tar cf - . | (cd destfolder; tar xvf -)
which won't copy resource forks either, but jpg photos don't have 
resource forks. Useful if you're only copying files without resource 
forks. The v in xvf means verbose - it lists the files as they are 
deposited. Omit if you don't want that, but it too can be useful.

rsync is also worth checking out. It looks complicated, but most of 
the complexity is to do with the case where the source or destination 
is on another machine.

David


-- 
David Ledger - Freelance Unix Sysadmin in the UK.
HP-UX specialist of hpUG technical user group (www.hpug.org.uk)
david.ledger at ivdcs.co.uk
www.ivdcs.co.uk