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Comments for afio

20 Oct 2004 12:17 kholtman

Re: >2GB file support status
Hi Jörg,

I checked this very carefully as part of designing afio 2.5: the GNU cpio in most Linux distros goes to 2GB-1 only, not 8GB-1. There are however some non-GNU non-Linux cpio versions that go >=2GB.

You are declaring the cpio format dead, but that is not an approach that I am taking. I like standards as much as the next guy but I care more about compatibility.

I designed afio 2.5 for maximum compatibility with the cpio that you get when you install a plain Linux distro, because this is the only thing people will have in some restore scenarios. afio 2.5 tries its utmost to stay compatible with this cpio, and will switch to non-compatible achive headers, with a warning message, only if it really has to. This is all explained at length in the manpage. You call this a bug, I call it a feature.

I would like OSes to support the 'pax' extensions, but out of the box they don't. I considered using the pax format when designing afio 2.5, but I decided against using it because the changes to the source would have been too great (would have created too many new bugs), plus it would break compatibility with cpio and old afio versions.

10 Oct 2004 06:20 schily

Re: xattr+acl
Natively supported by star since 3 years, however not for
CPIO based archives. The CPIO archive format
is hard to extend, while it is simple to extend TAR.

10 Oct 2004 06:16 schily

Re: >2GB file support status
Please be careful:

Althogh cpio supports file sizes op to 8 GB - 1 byte, afio creates proprietary and nonportable
archives for files >= 2 GB.
Even worse: afio will switch the archive format
in the middle of the archive. The proprietary format used for files >= 2G is not CPIO.

The CPIO format has been declared dead with
POSIX.1-2001 because it is not extensible for the
future. The TAR archive format has been extended
in a way that makes is infinitely extensible for
the future. Any recent OS should include support
for the POSIX.1-2001 tar extensions called "pax".
I would strongly dissuade from using cpio based archives for exchanging or storing data.

20 Sep 2004 02:41 kholtman

Re: xattr+acl
If afio is used in a backup script, the script can (theoretically) take care of backing up and restoring xattr+acl. Doing a google, it looks like the Mondo Rescue backup system can be used with afio to back up and restore xattr+acl.

If someone contributes some short scripts for xattr+acl backup and restore with afio, I (the current maintainer) will probably bundle them as examples with the afio sources.

Adding native support for xattr+acl in afio itself is not planned by me, or any contributer I know of. If someone wants to do it, I can give advice and some support, and will check and fold in the patch file.

19 Sep 2004 17:08 xose

what's about xattr+acl support for 2.6 kernels ?

21 Dec 2003 06:51 kholtman

>2GB file support status
The new 2.5 version now supports >2GB files, this makes the 2.4.8* betas obsolete -- please upgrade to 2.5.

04 Dec 2002 15:05 kholtman

>2GB file and archive support in afio-
A BETA release with >2GB file and archive support
is now available at: (

See the README.FIRST file included in the .tgz for the beta release notes.
If you have no >2GB needs then use of this beta is NOT recommended, use the stable afio 2.4.7 (non-beta) instead.

27 Nov 2002 13:37 kholtman

Latest >2GB support status
27 Nov 2002: I received several patches and feedback concering support
for >2GB archives and >2GB files. Support requires switching to an 8 byte off_t type which
may trigger latent bugs in afio on some platforms (one bug in this class has already been found).

Therefore, a BETA release will be done soon (within 7 days, watch this site), but a non-beta
release tested according to the usual standards will take longer (maybe months).

23 Sep 2002 18:13 kholtman

Status of support for archiving >2GB files
The archiving of >2GB files is not supported, mainly because of (current) limitations in the archive file header format. Support for this is on my (the current maintainer's) long-term list of things to do. If someone else wants to do it first, thet can contact me, if they want, for some thoughts and hints on how to do it in a semi-clean way.

23 Sep 2002 18:02 kholtman

Status of support for archives into >2GB files on a filesystem
When compiled on most linux installations, afio 2.4.7 will not be able to create archive files larger than 2 GB on a regular filesystem.

Experimental patches to fix this are included in the debian afio 2.4.7-7 package (package status is `unstable' -- get the package patch file on the debian site). After more testing these patches will likely go into the afio 2.4.8 release. There is no hard timeline for this release yet. As a workaround, the afio archive output can be piped into split(1) to create multiple output files each smaller than 2 GB.


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