Messages in this thread |  | | Date | Wed, 29 May 1996 09:03:04 +0100 (WET DST) | From | Klaus Lichtenwalder <> | Subject | Re: cdrom: "df" != real size ? |
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On Wed, 29 May 1996, Herbert Rosmanith wrote:
> venus:~# df > Filesystem 1024-blocks Used Available Capacity Mounted on > /dev/hda2 985329 493077 441348 53% / > /dev/scd0 94 94 0 100% /cdrom > > this does mean that there are 94x1024x1024 bytes = 94MB on CD? > or is this wrong ? I guess so, because when I tar the whole thing, > I'll see: > > venus:~# tar -cf cdrom.tar /cdrom/ > venus:~# ls -l cdrom.tar > -rw-r--r-- 1 root root 297768960 May 29 07:40 cdrom.tar > > but this would mean that 1 block on cdrom is 3093.510638 bytes each. > hmm ... where is the error? >
When you do a tar, that's everything but a close approximation to the real space used, especially if you have many (small) files in that tree. Tar creates a 512byte header for each file and pads the last block to 512 byte blocks. A closer approximation would be using cpio, that one only uses a small header and pads the file to the next even boundary. Check with /usr/include/tar.h.
Klaus
________________________________________________________________________ Klaus Lichtenwalder, Dipl. Inform., PGP Key: email to key@Four11.com Lichtenwalder@ACM.org, http://www.wp.com/Klaus, fax: +49-89-98292755 Check out Oregon vs. Schwartz: http://www.lightlink.com/spacenka/fors
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