Re: [ANNOUNCE] DualFS: File System with Meta-data and Data Separation

["Jörn Engel" <joern@lazybastard.org>]

On Thu, 15 February 2007 23:59:14 +0100, Juan Piernas Canovas wrote:
> >
> Actually, the version of DualFS for Linux 2.4.19 implements a cleaner. In 
> our case, the cleaner is not really a problem because there is not too 
> much to clean (the meta-data device only contains meta-data blocks which 
> are 5-6% of the file system blocks; you do not have to move data blocks).

That sounds as if you have not hit the "interesting" cases yet.  Fun
starts when your device is near-full and you have a write-intensive
workload.  In your case, that would be metadata-write-intensive.  For
one, this is where write performance of log-structured filesystems
usually goes down the drain.  And worse, it is where the cleaner can
run into a deadlock.

Being good where log-structured filesystems usually are horrible is a
challenge.  And I'm sure many people are more interested in those
performance number than in the ones you shine at. :)

Jörn

-- 
Joern's library part 14:
http://www.sandpile.org/