> 'dd' will at best get you a 500GB disk on your new 900G SSD.
Not at all. You can easily use the remaining space afterwards.
As for me, I indeed wouldn't use `dd` in your case. Because instead,
I'd move to LVM. I.e. setup an LVM volume group on your new disk, and
create logical volumes for / and /home (and maybe /boot as well since
Grub can now boot off of LVM, but I tend to keep my /boot partition
outside of LVM).
Then use `cp -a` (or `rsync`) to copy stuff from your old disk to the
new. You can definitely do that while the system is up and running (no
need to boot with some other live image. I've done that many times and
never had a problem), tho you probably do want to try and make sure that
it's sufficiently idle. If you want to use `dd`, then indeed you should
make sure the source partition is not mounted (or is mounted read-only),
otherwise you could end up with a new filesystem that's too corrupted.
Stefan
