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Re: [Bug-tar] High per file overhead?

From: Phillip Susi
Subject: Re: [Bug-tar] High per file overhead?
Date: Sun, 26 Feb 2006 18:23:05 -0500
User-agent: Mail/News 1.5 (X11/20060213)

Joerg Schilling wrote:

A quick look into the cpio source http://cvs.opensolaris.org/source/xref/on/usr/src/cmd/cpio/cpio.c#1216
verifies that there is no such format in cpio.

Maybe you are not talking about cpio but about one of many cpio clones.....

Since when is open solaris the only or one true unix system? That's rhetorical, no need to answer. Since this is the GNU tar mailing list, most people would correctly assume I was referring to the GNU cpio.

I also fail to see why you hold it up apparently in attempt to prove me wrong when I reaffirmed my statement that I was using the newc cpio format rather than considering that I maybe I wasn't either crazy or twice mistaken, and therefore, maybe was not using open solaris.

du only counts the file contend and a part of the meta data (not counting e.g.
the "inode" - see: /usr/include/sys/fs/ufs_inode.h)
Right, but the timestamps, owner, and mode only take up a handful of bytes, which cpio also stores.

The cpio archive format -Hcrc never has become a standard and the POSIX cpio 
has been declared obsolete 5 years ago because it it not extensible.

Less useful formats may have less overhead but this is an inferior argument
if you have to decide for a portable and extensible format. The POSIX cpio format is e.g. limited to 8 GB files and the SVr4 crc format is limiet to even less.
If you like to have an archive format that completely fits your actual needs,
you will end up wit > 100 incompatible archive formats.

If you compress the result, the remaining difference is less than 1%.
I'd say archiving my Maildir is a rather real world use, so this is somewhat relevant. I did notice though, that once compressed, the difference in size is greatly diminished.

See above.


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