Bob Friesenhahn <[EMAIL PROTECTED]> wrote:
> On Sat, 23 Feb 2008, Joerg Schilling wrote:
> >
> > Star typically needs 1/4 .. 1/3 of the CPU time needed by GNU tar ans it
> > uses two processes to do the work in parallel. If you found a case where
> > star is not faster than GNU tar andwhere the speed is not limited by the
> > filesystem or the I/O devices, this is a bug that will be fixed if you
> > provide
> > the needed information to repeat it.
>
> I re-ran my little test today and do see that 'star' does produce
> somewhat reduced overall run time but does not consume less CPU than
If you found this, I am not sure what you did meter.
gtar needs the same amount of system time as star does. This is not really
reducable. You may reduce the system time a bit with star if you tell star
to use a bigger FIFO size.
Approx. 90% of the user CPU time of a tar implementation is spend in the
creation of the tar archive headers. This is done much more efficiently by star
than by GNU tar. If you like to compare you should know the different archive
formats.
If you like to do backups, you need to check archive formats that include a
sufficient amount of file meta data.
If you like to do backups, you need a POSIX.1-2001 based tar archive that allows
extensions. If you like to create this archive type, you need 2x+ the amount of
USER CPU than with vanilla tar if you do not have an optimized algorithm.
Star only needs 1.7x the amount of user CPU time and star in POSIX.1-2001 mode
still needs less CPU time than GNU tar with vanilla old tar archives.
> Clearly none of these tools are adequate to deal with the massive data
> storage made easy with zfs storage pools. Zfs requires similarly
> innovative backup solutions to deal with it.
You did not test backuops yet and you can't if you include other tools
in your test....
Star implements true incremental bacakups. This is missing in cpio and this
is announced but not working with GNU tar.
Jörg
--
EMail:[EMAIL PROTECTED] (home) Jörg Schilling D-13353 Berlin
[EMAIL PROTECTED] (uni)
[EMAIL PROTECTED] (work) Blog: http://schily.blogspot.com/
URL: http://cdrecord.berlios.de/old/private/ ftp://ftp.berlios.de/pub/schily
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