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Re: ext3 on 2.4.4



"Stephen C. Tweedie" wrote:
> There are also ext3-specific features.  Ext3 already offers
> data-journaling, which allows synchronous data writes to be spooled to
> the journal sequentially.  So, synchronous write traffic such as
> sendmail spools or NFS servers can obtain fully consistent,
> synchronous data and metadata writes without seeking on the disk.
> Combine that with ext3 support for journaling to a separate spool disk
> and certain workloads will be enormously faster (we've already
> demonstrated external spool disks using a prototype ext3 variant which
> ran noticably faster than ext2).

Yes, I noticed this.  I've previously brought up the idea regarding
NVRAM journals or is there an "issue" with a particular company in
trying to move there (and no one can get hardware)?

> That means that having evolutionary and revolutionary filesystems at
> the same time is a Good Thing.  Stability is my number 1 priority for
> ext3.  That means that ext2 filesystems are 100% compatible with
> ext3: you never need to reformat.  It means ext3 takes advantage of
> the tried-and-tested ext2 fsck code.  It means that I don't want to
> break any existing ext2 functionality such as NFS or quotas, and that
> I reuse existing tested kernel code wherever possible, and try not to
> introduce performance bottlenecks that degrade existing ext2
> performance.  Other things such as the hash-indexed directory code are
> important but secondary to the stability concern.

You're preaching on the choir to that one!  I constantly have to
smack^H^H^H^H^Hcorrect those "ReiserFS absolutists" on that one. 
They bash Ext3, call it beta and announce ReiserFS "is the bomb"
just because their running Mandrake on their home system.  I try to
explain that "all OSS exists to 'scratch an itch'" and Ext3 is a JFS
that targets those who need an evolutionary solution based on
rock-solid and proven Ext2.  They usually stoop to "ReiserFS is
version 3.6, Ext3 is 0.0.6b" until I point out Ext2 is 0.5b.  ;-PPP

As far as "tried-and-tested ext2 fsck code," as you'll note in my /.
post, I had a physical disk error I was able to full recover from. 
Yeah, it took a ~60 minute Ext2 fsck, but I didn't lose _any_ data
other than in the areas where sectors were lost.

> That means that ext3 will *never* be btree-based.  If you want to
> explore the possibilities that a radical new filesystem structure
> offers, you need to make a different choice.  Choice Is good.

Which is what I was talking about with XFS, being that ReiserFS'
non-traditional structure is what keeps people like me from adopting
it on file servers.

-- TheBS

-- 
Bryan J. Smith, President        mailto:b j smith ieee org
(407)366-7013 pager:(888)694-5793 chat:thebs413 AOL/MS/Yho
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