  | Date: Fri, 19 Jul 2002 14:28:42 +0100
  | From: Niall O Broin 
  | 
  | I have about 60G of data which I need to copy from one disk
  | to another.  However, I'm not sure how I should best copy it.
  | The problem is the bulk of the data is images and most of these
  | image have two directory entries i.e. there is a hard link to
  | each file.  If I copy them using cp -a or my usual favourite of
  | find .|cpio -pmd other_dir  it's going to copy each file twice,
  | which is not what I want. dump / restore would take care of this
  | if the source filesystem wasn't reiserfs  :-(  Any suggestions ? do your (and my) favourite, it'll be Ok:  1. cpio(1) preserves hard links, i.e., if F1 and F2 are
     hard-linked and both are "copied", then the "copies"
     are also hard-linked.  this is true of all `cpio's
     (and `tar' and any other decent/usable archival tool,
     by definition (IMHO)).  2. `cpio -p' (at least `GNU cpio version 2.4.2') will only
     read/write (copy) the actual data bytes once.  I _think_
     this is true for all `cpio's (not just that GNU version),
     but am not certain. if you use an intermediate archive, e.g.:    cpio -o ... >file;   ...;   cpio -i ... <file then the actual data bytes are copied into the archive (file)
 under each name (e.g., as both F1 and F2).  but GNU `cpio' is
 smart about this in pass-through mode (`-p'), copying the data
 just once (or so I read the source).cheers!
	-blf-p.s. assuming this is a one-time operation that you won't repeat
    anytime soon (e.g., never; i.e., time isn't a major issue),
    and are not using any intermediate media/file (so storage
    isn't an issue), then even if `cpio' did read the data twice,
    so what? --- as long as, of course, it re-creates the hard
    links.  which it will.--
 Innovative, very experienced, Unix and      | Brian Foster    Dublin, Ireland
 Chorus (embedded RTOS) kernel internals     | e-mail: blf@utvinternet.ie
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