Re: getting creative with cp (was Re: cp -n diff)

[David Holland <dholland-tech%netbsd.org@localhost>]

On Fri, May 06, 2011 at 03:45:47PM -0400, der Mouse wrote:
 > > C) Speed it up some more: what if the kernel allowed for "lazy"
 > >    copies to be made when the source & destination were on the same
 > >    filesystem, and the filesystem supported it?
 > 
 > Filesystem-level COW would be a very nice thing to have.  I would
 > question whether it belongs in cp, though, or more precisely whether cp
 > should be aware of it.  I would prefer to have the filesystem
 > autodetect whenever a block is written that is identical in content to
 > a block already present and share the data.  (Yes, what I'm talking
 > about here borders on a content-addressed disk layer.)

There are filesystems that do that; we just don't have one.

However, an explicit fast clone operation for directory trees is also
a nice feature. There are filesystems that do fast clone of whole
volumes, but I don't think I know of one that does subtrees...

-- 
David A. Holland
dholland%netbsd.org@localhost