>On Thu, 2005-05-05 at 07:58, T. Horsnell wrote: > >> Oops, I spoke too soon... >> >> On my system: >> >> [root@ls1 ~]$ df -k /testnfs >> Filesystem 1K-blocks Used Available Use% Mounted on >> /dev/sdd1 35280616 11836988 21651476 36% /testnfs >> [root@ls1 ~]$ time tar cf - -C /testnfs . > /dev/null >> 0.074u 0.000s 0:00.07 100.0% 0+0k 0+0io 0pf+0w >> [root@ls1 ~]$ time tar cf /dev/null -C /testnfs . >> 0.075u 0.000s 0:00.07 100.0% 0+0k 0+0io 0pf+0w >> >> [root@ls1 ~]$ df -k /nfs/server1/www >> Filesystem 1K-blocks Used Available Use% Mounted on >> server1:/www 35278544 11923576 21562920 36% /nfs/server1/www >> [root@ls1 ~]$ time tar cf - -C /nfs/server1/www . > /dev/null >> 0.303u 1.739s 0:08.73 23.2% 0+0k 0+0io 0pf+0w >> [root@ls1 ~]$ time tar cf /dev/null -C /nfs/server1/www . >> 0.294u 1.333s 0:16.00 10.1% 0+0k 0+0io 0pf+0w >> >> [root@ls1 ~]$ tar --version >> tar (GNU tar) 1.14 >> Copyright (C) 2004 Free Software Foundation, Inc. >> This program comes with NO WARRANTY, to the extent permitted by law. >> You may redistribute it under the terms of the GNU General Public License; >> see the file named COPYING for details. >> Written by John Gilmore and Jay Fenlason. >> >> Les, is this *meant* to work as you say, or is it something >> which just happened to work (once upon a time)? If its meant >> to work, perhaps I should contact the Gnutar maintainers... > >It's intended to let the --totals option work as quickly >as possible, but now I remember it is even smarter. It >is comparing it's output fd inode to that of /dev/null >so even the redirection triggers the 'directory only' >mode. If you look at your file access times you'll see >that they weren't really read. You have to do something >like 'tar cf - . |cat >/dev/null' to make it actually >read the files and throw away the data. That cracked it. Thanks very much. Terry.
