[PATCH] adding two new options to 'cp'

Oliver Fromme olli at lurza.secnetix.de
Wed Aug 2 17:46:27 UTC 2006


Bakul Shah wrote:
 > Peter Jeremy wrote:
 > > As a general comment (not addressed to Tim):  There _is_ a downside
 > > to sparsifying files.  If you take a sparse file and start filling
 > > in the holes, the net result will be very badly fragmented and hence
 > > have very poor sequential I/O performance.  If you're never going to
 > > update a file then making it sparse makes sense, if you will be
 > > updating it, you will get better performance by making it non-sparse.
 > 
 > Except for database tables how common is this?

For example image files of media, e.g. ISO9660 images
or images of hard disk partitions.  I often have to handle
such images, and I certainly do _not_ want them to be
sparse.

Before someone adds a bogus "sparse file support" option
to cp(1), I would rather prefer that someone fixes the
existing -R option which currently doesn't handle hard-
links correctly.
That flaw is documented in the manual page, so it might
not count as a "bug", but it's a flaw nevertheless.  A lot
of people -- even so-called professional admins -- use
"cp -Rp" to copy directory hierarchies, and afterwards
they wonder why the copy takes up much more space than
the original, because all hardlinks have been copied as
separate files (if they notice at all).

Oh by the way:  Linux' option for sparse file handling
is "--sparse", and there is no one-letter option (both
-s and -S exist, but have nothing to do with sparse
files).  So there wouldn't be an easy way for FreeBSD to
stay compatible with Linux.

Best regards
   Oliver

-- 
Oliver Fromme,  secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing
Dienstleistungen mit Schwerpunkt FreeBSD: http://www.secnetix.de/bsd
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        -- Richard A. O'Keefe


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