On Wed, 9 May 2007, Steinar H. Gunderson wrote:
On Wed, May 09, 2007 at 01:57:51AM -0700, david@xxxxxxx wrote:
given that RAID, snapshots, etc are already in the linux kernel, I suspect
that what will need to happen is for the filesystem to be ported without
those features and then the userspace tools (that manipulate the volumes )
be ported to use the things already in the kernel.
Well, part of the idea behind ZFS is that these parts are _not_ separated in
"layers" -- for instance, the filesystem can push data down to the RAID level
to determine the stripe size used.
there's nothing preventing this from happening if they are seperate layers
either.
there are some performance implications of the seperate layers, but until
someone has the ability to do head-to-head comparisons it's hard to say
which approach will win (in theory the lack of layers makes for faster
code, but in practice the fact that each layer is gone over by experts
looking for ways to optimize it may overwelm the layering overhead)
Whether this is a good idea is of course hotly debated, but I don't think you
can port just the filesystem part and call it a day.
Oh, I'm absolutly sure that doing so won't satidfy people (wnd would
generate howles of outrage from some parts), but having watched other
groups try and get things into the kernel that the kernel devs felt were
layering violations I think that it's wat will ultimatly happen.
David Lang
