Re: [Ext2-devel] [RFC 0/13] extents and 48bit ext3

[Andreas Dilger <adilger@clusterfs.com>]

On Jun 09, 2006  21:09 -0400, Jeff Garzik wrote:
> Theodore Tso wrote:
> > Jeff, you seem to think that the fact that the layout isn't precisely
> > the same after an on-line resizing is proof of something horrible, but
> > it isn't.  The exact location of filesystem metadata has never been
> > fixed, not in the past ten years of ext2/3 history, and this is not a
> > big deal.  It certainly isn't "proof" of on-line resizing being
> > something horrible, as you keep trying to claim, without any arguments
> > other than, "The layout is different!".  
> 
> No, I was proving merely that it is _different_.  And the values where 
> you see a _difference_ are the ones of which are no longer sized 
> optimally, after you grow the fs to a larger size.

It sounds like you don't know what you are talking about, which is OK,
except that you keep harping on some non-existent point.

> So you incur a performance penalty for resizing to size S2, rather than 
> mke2fs'ing the new blkdev at size S2.  Certainly within the confines of 
> ext3 that cannot be helped, but a different inode allocation strategy 
> could improve upon that.

???  Can you please be specific in what the performance penalty is, and
what specifically is "not sized optimally" after a resize?  How exactly
does inode allocation strategy relate to anything at all to online resizing.

Given that Ted and I are both disagreeing with you, and we are the two
people who know the most about the online resizing code (SCT is also
in this same group), maybe you should just concede that you are incorrect
on this point and move on.

Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.