moving fs to new disk using tar

[Richard Hector <rhector@paradise.net.nz>]

Hi all,

I thought I was being very careful, but this didn't work like I'd hoped.

Basically I want to move my /usr fs from one disk to another - the first
will eventually be repartitioned, to use LVM and ReiserFS. Other
filesystems will follow.

So I used this command from / (in single user mode - that's what "init 1"
does, right?):

tar -c --atime-preserve -l usr |tar -C /spareide -x -v --atime-preserve
  --preserve --same-owner

I wasn't entirely clear from the man page which options were intended for
use with creating and which with extracting the archive, so when in doubt
I used it for both.

Now, my understanding was that the "-C /spareide" should have started the
extraction from where my nice empty filesystem was mounted on
/spareide/usr - but this didn't happen. It appears to have extracted over
itself in /usr, giving lots of warnings about files changing while they
were being read (not all of them - maybe only the big ones?), and changing
dates on some of them (again not all - dunno why) as well.

I'm guessing I've made some fairly fundamental mistake somewhere - any
suggestions?

My other thought was that it would be nice to do all this with both
filesystems unmounted - are there tools for that?

Many thanks,

Richard