Re: Does mv Preserve Hard Links?

[Bob Proulx]

address@hidden wrote:
>     mv /mnt/fs1/dir /mnt/fs2/dir
> 
> where /mnt/fs[12] are two different ext3 filesystems, /mnt/fs2/dir
> doesn't exist, and /mnt/fs1/dir contains many thousands of files,
> several thousand of which are reference by 3 to 6 directory entries
> compared to the normal 1.
> [...]
> I've got lots more moving to do so I'd like to determine if there are

This is an orthogonal answer.  Personally I highly recommend using
'rsync' for what you are wanting to do.  It has several advantages.

 * You can interrupt it without issues of partial data movement
 * You can restart it
 * You can run it several times on the same data without issue
 * It can optionally preserve hardlinks

Example:

  rsync -a --hard-links /mnt/fs1/dir /mnt/fs2/

Hint: Don't specify the target directory.  The rsync rule is that if
it is a directory then the result is in that directory and you get one
more directory than you probably wanted.

If you have a large amount of data but don't want to take the original
offline from users you can make a copy ahead time and then sync the
final changes quickly when you are ready to make the switch.  In that
case use the --delete option to make an exact copy including removing
files that have been deleted.  Deletion can be dangerous so I always
check that I have the directories lined up right with the -n option
first and then run without the -n when I am sure I have things right.

Use the --delete to make an exact copy, testing with -n first.

  rsync -n -av --delete --hard-links /mnt/fs1/dir /mnt/fs2/

After verifying that is what I want then run without the -n.

  rsync -av --delete --hard-links /mnt/fs1/dir /mnt/fs2/

Bob