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



Bryan:

	First off I will say I never knew any of the things that you say
about XFS, and if it is all true (and I have no reason to think
otherwise), then I will try XFS out, and see what it gets me. This
thread had initially started because I had asked why when I formatted an
EXT3 16GB partition I would have 14GB free, and when I formatted the
very same partition with ReiserFS I have 16GB free. It was not even a
matter of curiosity in as much as I noticed it only after the restore of
my files failed, predicated upon their not being enough space to restore
to, and I knew the partition had not changed in sizes from what it was
prior to the backup and reformatting of it.

	While I can have appreciation for the security in terms of
quotas and ACLs, again for a laptop user of Linux, it is not as big a
concern for me, as it would be if I were running a server.

	If EXT3 gains tail packing soon (presuming this is part of the
difference as to why my 16GB partition did not restore from tape when
the partition was formatted as a 16GB EXT3, and had enough space when
reformatted as ReiserFS 16GB partition), then I would move back to EXT3.
Whatever happened when I used EXT3, I had 14GB of free space, not 16GB
free (as I did with ReiserFS), and it prevented all the data from being
restored since there wasn't enough room.


Very Respectfully, 

Stuart Blake Tener, IT3 (E-4), USNR-R, N3GWG 
Beverly Hills, California
VTU 1904G (Volunteer Training Unit) 
stuart bh90210 net 
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JOIN THE US NAVY RESERVE, SERVE YOUR COUNTRY, AND BENEFIT FROM IT ALL. 

Sunday, January 13, 2002 4:38 AM


-----Original Message-----
From: bs linux-wlan com [mailto:bs linux-wlan com] On Behalf Of Bryan J.
Smith
Sent: Monday, February 04, 2002 4:13 PM
To: stuart bh90210 net
Cc: ext3-users redhat com
Subject: Re: 2GB of Waste? How can it be?

"IT3 Stuart Blake Tener, USNR-R" wrote:
>         The only reason I am not using EXT3 (I think using the more
> advanced journaling methods, it is a stronger product), is that I am
> very concerned about maximizing the space I get out of my laptop hard
> drive, that is my main concern, next to the filesystem being stable (I
> consider EXT3 and ReiserFS to both be stable at this point).
>         Perhaps it is time for me to evaluate again EXT3, and look at
> how much the space difference is. It sure is convenient to use the
> filesystem that the distribution wants you to pick as the default, and
> EXT2/EXT3 is well thought of.

Er, free disk space is not going to be a fs-implementation issue. 
ReiserFS has a B*Tree that more than make up for its "inode
efficiency" issue, although it depends on what is stored.  I think
the B*Tree is pre-allocated/reserved in V3 (anyone?), which eats up
several tens of MB anyway.  But this adds up to pennies in the end.

But even if you still consider it "essential," then XFS is a
_even_better_alternative_ to ReiserFS V3!  In addition to its
dynamic inode allocation, XFS can store a small file's data in its
inode, for space savings (i.e. doesn't use a data block).  ReiserFS
still requires you to eat a 4KB (or whatever the basic size is) data
block, _in_addition_ to eating _both_ inode pointer space _and_
space in the B*Tree.  XFS also stores symlinks in the inode as well
(saving a datablock versus Ext2/3), although ReiserFS stores
symlinks in its B*Tree for about the same "cost" in the end.  XFS
does other inode/freespace management much better than ReiserFS V3
IMHO (except for lots of deletes, then XFS does slow).

[ Information according to a Linux Gazette #55 comparison of the
four major JFS' for Linux, located here:
http://www.linuxdoc.org/LDP/LG/issue55/florido.html ]

And as you found out, the "reservation" of disk space can be changed
on-the-fly with "tune2fs", although don't expect good performance
out of _any_ filesystem that is less than 5% free (like
_detrimental_ ;-).

> It is also that I know ReiserFS is coming out with V4, which is
> supposed to have encryption built it as well, and again, that
> will also be important to me.

ReiserFS V4 is _far_ from being adopted in the stock kernel AFAIK. 
Heck, one of the reasons why ReiserFS V3 had "trouble" getting into
the stock kernel, from what I understand, is that Linus required
Namesys to "tie down" the actual structure.

That's not to say ReiserFS V4 won't be excellent, and I like a lot
of what I see in it (and ReiserFS in general).  But from your
"viewpoint" that "RedHat should put it in the installer as standard"
-- sorry, not going to happen, not in-line with what most RedHat
consumers (at least AFAIC) want.

Hence which makes your posts here somewhat ... how should I say ...
less-than-interesting???

-- Bryan

P.S.  Anyone should feel free to correct me where my
information/assumptions are wrong.

-- 
Bryan J. Smith, Engineer        mailto:b j smith ieee org   
AbsoluteValue Systems, Inc.     http://www.linux-wlan.org
SmithConcepts, Inc.          http://www.SmithConcepts.com
---------------------------------------------------------
1999 IRS Data:  The top 1% of income earners pay over 36%
of the taxes, but have less than 20% of the total income.





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