[ale] [Robert.L.Harris at rdlg.net: Reiser vs EXT3]

[Charles Shapiro]

I just got back from Linux Lunacy 2, where one of the highlights was
Theodore Ts'o talking about filesystems. He led the team which wrote
both ext2 and ext3. My notes on the class are at
http://tomshiro.org/pubtwiki/ALE/LinuxLunacyTwo/day3.txt. Theodore of
course is not terribly enchanted with reiserfs. ext3 is exactly ext2
with journaling added -- basically this means that file metadata is
written twice, once to a journal and again to the actual disk. Since you
never seek on the journal, this is pretty reasonably fast -- it's always
a block write, which is pretty cheap. When the machine boots after a bad
shutdown, it copies the most recent metadata back from the journal to
the disk to ensure that everything is self-consistent. 

We've been using ext3 here at the office for some time, and we've
noticed no speed degradation compared to ext2.  

I can't speak to reiserfs since we don't use it here. But even mr.
Reiser admits that Weird Things can happen to reiserfs if your machines
crash -- e.g. the crash can mung files which were closed hours before.
Scary stuff, to me. My notes have more detail on this. Also, performance
of all of these file systems varies dramatically with workload and
hardware. As I understand it, reiserfs is a lot better with lots of
small files, but as average file size rises its performance comes 
closer to ext2. Again, check my notes for details -- it's discussed at
about slide 15.

-- CHS

On Thu, 2002-10-31 at 12:53, Jim Popovitch wrote:
> Hi Robert,
> 
> I have seen similar... and have just assumed that Reiser was more robust due
> to it's age.  It is also worth pondering whether ext3 has more overhead
> since it continuously maintains ext2 compatibility along the way.
> 
> -Jim P.
> 
> > -----Original Message-----
> > From: Nomad the Wanderer [mailto:nomad at rdlg.net]On Behalf Of Robert L.
> > Harris
> > Sent: Thursday, October 31, 2002 9:54 AM
> > To: Atlanta Linux Enthusiasts
> > Subject: [ale] [Robert.L.Harris at rdlg.net: Reiser vs EXT3]
> >
> >
> >
> > I bounced this to the Kernel list but they may be a bit busy with the
> > new release.  Thoughts/theories?
> >
> >
> >   Still working on that replacement mail server and a new rumor has hit
> > the mix.  It follows that reiserfs is much faster than ext3 (made ext3,
> > not converted from ext2 if it matters) and this is causing some
> > problems.  On a 200Gig filesystem is this truely an issue?
> >
> > Thanks,
> >   Robert
> >
> >
> > :wq!
> > ------------------------------------------------------------------
> > ---------
> > Robert L. Harris
> >
> > DISCLAIMER:
> >       These are MY OPINIONS ALONE.  I speak for no-one else.
> > FYI:
> >  perl -e 'print
> > $i=pack(c5,(41*2),sqrt(7056),(unpack(c,H)-2),oct(115),10);'
> >
> >
> > ---
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> >
> >
> 
> 
> 
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