From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nikolai Joukov Subject: Re: [ANNOUNCE] RAIF: Redundant Array of Independent Filesystems Date: Fri, 22 Dec 2006 22:21:47 -0500 (EST) Message-ID: References: <200612161635.49502.a1426z@gawab.com> <200612172059.07941.a1426z@gawab.com> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org Return-path: To: Al Boldi In-Reply-To: <200612172059.07941.a1426z@gawab.com> Sender: linux-raid-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org > > 3. A known ideal solution for this problem is sharing of the cached pages > > between file systems. We attempted to do it for Tracefs but the > > resulting code is not beautiful and is potentially racy: > > > > Unfortunately, for fan-out file systems this solution requires even > > more support from the OS. However, this is what most OSs do > > (including BSD and Windows) but unfortunately not Linux :-( > > VFS-hooks seem to be the cleanest solution not only for a stacked-fs, but > also for many other situations. It's rather sad that linux hasn't seen the > light yet. Jeff Sipek just got his proposal for a paper/discussion topic accepted to the Linux Storage and Filesystems workshop, co-located with FAST. The topic for discussion will be what "surgery" the Linux kernel needs to support stackable file systems properly. I hope it is an indicator that the situation with support of the stackable file systems in Linux may improve soon. Nikolai.