Nikos Chantziaras <rea...@arcor.de> wrote:
> On 08/14/2009 05:47 AM, meino.cra...@gmx.de wrote:
> > Hi,
> >
> > I am looking for a faster way to do a
> >
> > cp -a r<thisdir> <thatdir>
> >
> > locally on one machine with one harddisk inside.
> >
> > Is there a neat trick to accomplish this faster than
> > good old cp?
>
> Nope. Some people like to use pipes in hope to speed it up, something like:
>
> tar -c <thisdir> | tar -xC <thatdir>
>
> but this isn't really faster and fscks up sparse files.
Pipes definitely do not speed up things, they slow things down as pipes
introduce a significant system overhead.
The fastest method for copying directory trees (typicalls 30% faster than any
other known method) is to use star:
star -copy -p -xdot -acl -sparse -C <fromdir> . <todir>
Do not forget the '.' !!!!!
Note that on Linux you may _need_ to add "-no-fsync" because file I/O is slow
on Linux. On Solaris, not using -no-fsync slows things down by aprox. 10% but
allows star to grant that everything was really copied to stable storage.
On Linux, ot using -no-fsync slows things down by aprox. 400%, this is why
I recommend to add "-no-fsync". BTW: other programs behave like star
"-no-fsync" by default.
It may help to speed up things (in case you have enough RAM) to add: fs=128M
Use no more than 1/2 of the physical RAM as FIFO size.
Star implements the most effective way since more than 20 years. The idea is
to use a FIFO made of shared memory and to let star fork by default into two
processes that work independently.
Jörg
--
EMail:jo...@schily.isdn.cs.tu-berlin.de (home) Jörg Schilling D-13353 Berlin
j...@cs.tu-berlin.de (uni)
joerg.schill...@fokus.fraunhofer.de (work) Blog:
http://schily.blogspot.com/
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