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RE: 2GB of Waste? How can it be?



Dr. Tweedie, et al.:

	I understand that modifying ext2/ext3 absent backwards
compatibly is a big deal, but I think adding that function would be a
wonderful thing.

	I also would like to see RH 7.2 be able to install into a
ReiserFS filesystem (or any type of filesystem with Linux, Mandrake
allows this), and think it is somewhat arrogant of RedHat to disallow
that option in the installer. Notwithstanding that fact, I have made
ReiserFS work as my root partition, I just cannot get ReiserFS on RH 7.2
to boot up when devfs=mount is used.

	According to some experts I have asked at an installfest, the
issue seems to be more of a mount/RedHat/devfs integration issue more
than a ReiserFS issue, so that is why I am think this is not a foreign
forum to ask this question, since you might have had similar issues with
ext2/ext3.

	What I am aiming to accomplish is something like this: while
using an initrd image, to get RH 7.2 to boot up using ReiserFS as the
root partition while specifying devfs=mount inclusive as a boot option
in GRUB. I got half way done, and I do have RH 7.2 booting Linux with
ReiserFS as the root partition, it just does not work when I add
devfs=mount.

	I am going to copy down the error messages, and repost it here.
Perhaps one of the gurus here will know why it fails to work for me, or
will have a brilliant insight into what I missed which was obvious (that
happens to me a lot).

	The last piece of the puzzle (for me), when this is done, would
be to add a layer of encryption (using the loop-aes package, see
sourceforge.net if it interests you) in between the hardware and
ReiserFS with initrd. This can be done with little problem, but I am
saving it for last until I get ReiserFS booting with devfs=mount first.

	I appreciate everyone's assistance in advance and thank you for
your time.


Very Respectfully, 

Stuart Blake Tener, IT3 (E-4), USNR-R, N3GWG 
Beverly Hills, California
VTU 1904G (Volunteer Training Unit) 
stuart bh90210 net 
west coast: (310)-358-0202 P.O. Box 16043, Beverly Hills, CA 90209-2043 
east coast: (215)-338-6005 P.O. Box 45859, Philadelphia, PA 19149-5859 

Telecopier: (419)-715-6073 fax to email gateway via www.efax.com (it's
free!) 

JOIN THE US NAVY RESERVE, SERVE YOUR COUNTRY, AND BENEFIT FROM IT ALL. 

Sunday, January 13, 2002 4:38 AM


-----Original Message-----
From: Stephen C. Tweedie [mailto:sct redhat com] 
Sent: Monday, February 04, 2002 10:50 AM
To: IT3 Stuart Blake Tener, USNR-R
Cc: 'Stephen C. Tweedie'; ext3-users redhat com
Subject: Re: 2GB of Waste? How can it be?

Hi,

On Mon, Feb 04, 2002 at 10:40:47AM -0800, IT3 Stuart Blake Tener, USNR-R
wrote:
 
> 	Why cannot ext2/ext3 allocate inode space on a dynamic basis?

It's a fundamental design property inherited from the typical Unix
filesystems which existed at the time ext2 was designed.  There are
some parts of Unix semantics which actually make it very hard to
design a filesystem in a different way (reiserfs people will tell you
just how painful it is to have to support NFS if you have dynamically
allocated inodes.)

> 	More importantly why is it not possible to amend the number of
> inodes an ext2/ext3 filesystem has after the point of doing an mke2fs?

The whole way in which inode numbers get mapped to a disk block relies
on static allocation.  We're looking at ways to do dynamic allocation,
but it is *highly* non-trivial to do so in a backwards-compatible
manner.

> 	I modified my RedHat installation to boot up using a root
> filesystem of ReiserFS, but when I try to use devfs=mount along with
an
> initrd, it seems to give me some errors (initrd= something or other
> error, I will write it down next time). Any ideas?

Not without the error, no!

> 	What command do I give to tune2fs to change the space
> reservation percentage?

"man tune2fs"

> 	Also, I noticed that if I turn on ext3 journaling, I can no
> longer resize the partition with partition magic. So I am curious, how
I
> can completely revert an ext3 partition back to ext2 (temporarily) so
I
> can resize it, and then make it ext3 again. Is there a command line
> parameter for tune2fs which will reverse a "tune2fs -j"?

Yes -- "tune2fs -O ^has_journal" will clear the journal flag, and then
"e2fsck" will clean up the other bits that need to be cleared.

Cheers,
 Stephen





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