:
:On Wed, Feb 16, 2005 at 01:03:38PM -0500, David Rhodus wrote:
:> Soft updates and journaling are not the same thing.
:
:I know and I didn't say that. But soft updates allow a non-journaled
:filesystem to be implemented with much less things to worry about.
:E.g. NetBSD has support for ext2 uses the soft update code.
:Even in a journaled filesystem, the general concept can be used to
:keep track of what has to be journaled and what not.
:
:> I haven't done
:> any testing yet but I don't think FFS would perform as a very good
:> modern filesystem if we remove soft updates without changing the
:> behaviour of the filesystem.
:
:The performance of FFS without soft updates [read sync mounted] would
:be abysmal for stuff like cvs update. I don't consider async mount
:valid for anything but mfs. Linux user tend to disagree on that.
:
:Joerg
FFS also has a serious issue with the way it lays out directories.
In particular, it cannot handle large directories efficiently. The
dirhash code works up to a point but is a pretty nasty hack to try to
get around this limitation.
-Matt
Matthew Dillon
<dillon@backplane.com>