Re: [9fans] portable filesystem (was: spaces in filenames (and filesystems...))

[Digby Tarvin <digbyt@acm.org>]

On Thu, Apr 28, 2011 at 02:35:56PM +0200, dexen deVries wrote:
> On Thursday 28 of April 2011 14:11:27 Digby Tarvin wrote:
> > On a slightly related topics, one of my constant headaches lately
> > is the problem of deciding what filesystem to put on large capacity
> > removeable storage to give me maximum interoperability...
> >
> > What I really want is somthing that I can copy files to and from
> > from any of my OSs without losing meta-data.
>
> ext2/ext3 seems to work between windows and linux for free [1], and macos x
> with some payment [2] or perhaps for free via FUSE.
> surprisingly, you can even use LUKS [3] with it and it still works r/w between
> windows and linux.
>
> no idea about p9, sorry, but there used to be a r/o ext2 driver.
>
> you can freely convert filesystem between ext2 and ext3 mode on linux.

Thanks. I did experiment with a couple of Windows based ext2/ext3 options
a while ago, with limited success. I dont remember the details, but the
filesystem I wanted to read was rejected with an obscure error message.
I think the fac suggested re-formatting my filesystem might help, and
that put me off.

But as I said, that was quite a while ago, so maybe it is worth revisiting.
Ext2fsd looks promising.

However I do wish that at least the Unix world would settle on a common
filesystem format to support (in addition whatever is native) other than
FAT32 or NTFS. I dont currently use MACOS X, but I do use BSD on some
servers. If I go Ext2/Ext3 then I am probably reducing my interoperability
with more esoteric operating systems, which might be livable but is
unfortunate.

> at some point i had that crazy idea to have a pendrive formatted in ext3 or
> nilfs2, with small auxiliary partition with a virtual machine -- and use the
> virtual machine as a filesystem server when on hostile OS.

Not a bad idea, but you probably want an intelligent device able to
run the virtual machine itself (in which case it isnt really virtual),
otherwise you are limited to hostile os's with virtual machine support.

Perhaps a file server on a wireless or usb equipped smart phone...
I have a small wireless hotspot that also can serve files from an
optional MicroSD.

But I am thinking more of the 2TB or more USB drives that are now
quite affordable, but more useful if not tied to a single OS.

> personally, i'd love to have nilfs2 [4] ported to p9 and windows; but i guess
> it's matter of future.

Nice. I hadnt come across that one.

But What I think is really needed for this sort of application is a
filesystem with:
	Minimal restrictions of file size (64 bit addresses)
	Maximum versatility in FS topology (hard link support etc)
	Minimal restriction on file names (character set, length)
	Maximum support for all conceiveable meta-data.

My off the top of the head solution would be a filesystem were each file
has two open ended data forks. One for conventional file content, and the
other used for tagged meta-data. Each OS supporting the filesystem would
be able to define meta-data fields such that all meta data meaningful to the
original filesystem could be retained in files copied to the removeable
system, and mapped to ANSI equivalent standards meta data fields where
appropriate. File accesses would interpret native metadata with fallback
to the ANSI as required. I suppose it should even be able to suport slashes
and nulls in file names, although that would make such fules hard to
deal with from Unix.

At least it would be usable as a universal backup and file transfer medium.

Failing that, a simple and universally adopted filesystem - like FAT, but
without the stupid limitations, would be a step forward.

Regards,
DigbyT
--
Digby R. S. Tarvin                                          digbyt(at)digbyt.com
http://www.digbyt.com