Re: [RFC] Ext3 online defrag

[Dave Kleikamp <shaggy@austin.ibm.com>]

On Thu, 2006-10-26 at 09:37 -0400, Theodore Tso wrote:
> On Thu, Oct 26, 2006 at 04:36:48PM +1000, David Chinner wrote:
> > > > Remember, I'm not just talking about defrag - I'm talking about
> > > > an interface that is actually useful to apps that might care
> > > > about how data is laid out on disk but the applications writers
> > > > don't know anyhting about how filesystem X or Y or Z is
> > > > implemented. Putting the burden of learning about fileystem
> > > > internals on application developers is not the correct solution.
> 
> If all you want is something for applicaiton developers, about all you
> can do is to tell the filesystem, "create the file so that it will be
> quickly accessed after accessing this file or this directory".  I
> really don't see the point of having the application specify block
> numbers if you're also claiming the applicaiton isn't going to know
> anything about the filesystem layout --- or even the RAID layout of
> the filesystem.  I don't think it's at **all** useful to be
> half-pregnant on this score.

I think a utility such as a defragmenter should know about about the
filesystem layout.  I also think that it would be a good thing to have a
consistent interface so that every filesystem isn't implementing a
completely different one.
-- 
David Kleikamp
IBM Linux Technology Center