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Re: Raw EXT3 block format



Hello Andreas,

> On Apr 03, 2002  17:16 +0200, Pieter De Wit wrote:
> > I am looking to extend/create a file system that span networks/device of
any
> > kind, shape and manner :) Check out http://www.insync.za.net/openufs/
(also
> > on http://openufs.sourceforge.net - but I am not here to adv. the site
!)
>
> First note - UFS is a really bad name for this project, because this is
> commonly used for "Unix File System", which is used by Sun, HP, BSD, etc
> as their primary filesystem.  Linux even has a driver for this (see
fs/ufs).

Darn, double darn, triple darn, darn to the power of 64 (hehehehe)

I will have to think of something else. I think the name is gonna come
later....<g>

>
> > I would like to know, where can I find what EXT3 will write to the disk,
> > how it works etc.
> >
> > Surely EXT3 will write something like this :
> >
> > Block 0 - (1024 bytes) {DATA}
> > Block 1 - (1024 bytes) {FAT type block}
>
> This data is described in many places on the net (a good starting point
> would be Ted's http://e2fsprogs.sourceforge.net/ site, which has links
> to such documentation).  The ext3 filesystem has exactly the same
> on-disk layout as ext2 does.  It looks like you have a background with
> MSDOS/FAT filesystems?
>

Thanks, I will try them out, I have had some work on an FS, I wrote my own
FS *years* back and never had it working 100% (FS in a file on MSDOS/Windows
95). I now have a project/chance to get the "off-site backup" option to work
on. What the project is about, is to allow users to make off-site backups of
there systems (the idea started before I knew Linux :( ) and then restore
it. The problem with some other project is that these option are over HTTP
and not secure not to mention speed... The other problem is space, What do
you do when a users home dir. gets to more then your free space. Lets say a
corporate signs up 500 gig of disk space. There is no way that you can mount
that under one system. I have updated my docs on my site, the only problem
is that fingers type slower than the mind can think. Because I dev. the
system myself, I can port "user-space" apps (like the backup thing) to
Windows,Mac and whatever OS. I havn't looked at your site yet, but the
problem is Inter-OS-connection with most Network FSes, sure, you can mount
the FS under Linux and then Export it with SAMBA or NFS, but that is a pain
if you wanted to do this over the net. NFS might work, but I havn't found a
nice/stable NFS client for Windows....

> > Hope this makes sense.....
>
> Yes, this is actually a very interesting project.  In fact, I'm part
> of a team working on a distributed ext3 implementation right now
> (see http://www.lustre.org/ for details).
>
> Not to be overly negative, but it would seem that if you do not even
> know how ext3 stores its data on disk, it would seem a very difficult
> challenge to write a distributed ext3 implementation.  If you are
> really interested in working on something like this, I'd consider
> downloading the Lustre code and seeing how it works first.  We have
> "Lustre Lite" partly working already, which distributes metadata and
> data storage across servers, along with the beginnings of a lock manager.
>
> If you are still interested, you may consider contributing to Lustre -
> it is fully Open Source (GPL) software.
>
> Cheers, Andreas
> --
> Andreas Dilger  \ "If a man ate a pound of pasta and a pound of antipasto,
>                  \  would they cancel out, leaving him still hungry?"
> http://www-mddsp.enel.ucalgary.ca/People/adilger/               -- Dogbert
>

I will check it out....I already have some idea on how a FS works in
genral...but I am gonna study the ext2 code really well.

Thanks for all the help again !

Good luck for your project !

Cheers,

Pieter





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