From owner-freebsd-hackers Fri Mar 3 10:42:56 2000 Delivered-To: freebsd-hackers@freebsd.org Received: from acl.lanl.gov (acl.lanl.gov [128.165.147.1]) by hub.freebsd.org (Postfix) with ESMTP id 7486937C029 for ; Fri, 3 Mar 2000 10:42:44 -0800 (PST) (envelope-from rminnich@lanl.gov) Received: from mini.acl.lanl.gov (root@mini.acl.lanl.gov [128.165.147.34]) by acl.lanl.gov (8.8.8/8.8.5) with ESMTP id LAA378078 for ; Fri, 3 Mar 2000 11:42:43 -0700 (MST) Received: from localhost (rminnich@localhost) by mini.acl.lanl.gov (8.9.3/8.8.8) with ESMTP id LAA01485 for ; Fri, 3 Mar 2000 11:42:43 -0700 X-Authentication-Warning: mini.acl.lanl.gov: rminnich owned process doing -bs Date: Fri, 3 Mar 2000 11:42:43 -0700 (MST) From: "Ronald G. Minnich" X-Sender: rminnich@mini.acl.lanl.gov To: freebsd-hackers@FreeBSD.ORG Subject: Re: Copy-on-write filesystem In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Fri, 3 Mar 2000, Michael Bacarella wrote: > Can someone tell me why copy-on-write filesystems would be bad? It's a good idea. Peter Braam and I have written a device (called memdev) for linux (sorry!) that implements a virtual-memory-backed copy-on-write block device (like the loopback device, but uses anon vm pages for store). It's pretty interesting. It's quite fast, and copy-on-write does seem to work OK for a filesystem. I'm using this thing as one of two pieces of a new private name space implementation that would also work quite well on freebsd. note it's not really a file system, but a loopback block device which does copy-on-write for new blocks. You can also use it to easily implement translucent file system behaviour. ron To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message