From owner-freebsd-fs@FreeBSD.ORG Mon Feb 13 16:18:13 2012 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 91526106566B for ; Mon, 13 Feb 2012 16:18:13 +0000 (UTC) (envelope-from toasty@dragondata.com) Received: from mail-gy0-f182.google.com (mail-gy0-f182.google.com [209.85.160.182]) by mx1.freebsd.org (Postfix) with ESMTP id 4F9308FC14 for ; Mon, 13 Feb 2012 16:18:12 +0000 (UTC) Received: by ghbg15 with SMTP id g15so3133498ghb.13 for ; Mon, 13 Feb 2012 08:18:12 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=dragondata.com; s=google; h=from:content-type:content-transfer-encoding:subject:date:message-id :to:mime-version:x-mailer; bh=GuGCCon2EXlWczzIPiQsBTH39q4ElJxOY+/wJVnSR1I=; b=qGauxOFd5j2TdKABoULCfGA+P2wbs83dbLxhX8V1QOkCPBDqfp2lTTVrrgfEsYSdg1 EVY/4Z7ggo1WH+3u+UCP6KRuCV+LlgywWgdQIqcljMgHzSyW/7iLV2yiSDw8YaU+u/9X rcW07gY7RoY2IkLRHOiA1FaCSW1K0xUyYvZAI= Received: by 10.50.34.202 with SMTP id b10mr28204533igj.2.1329148545481; Mon, 13 Feb 2012 07:55:45 -0800 (PST) Received: from static177.us.your.org (static177.us.your.org. [204.9.55.177]) by mx.google.com with ESMTPS id en8sm8929719igc.5.2012.02.13.07.55.43 (version=TLSv1/SSLv3 cipher=OTHER); Mon, 13 Feb 2012 07:55:44 -0800 (PST) From: Kevin Day Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Date: Mon, 13 Feb 2012 09:55:36 -0600 Message-Id: To: freebsd-fs@freebsd.org Mime-Version: 1.0 (Apple Message framework v1251.1) X-Mailer: Apple Mail (2.1251.1) X-Gm-Message-State: ALoCoQlm5ha3OgxLIwU3qFkJ+WntX81Oiu40fKFE31fWJ4KNtTftEBmd0KtYeY2uFVHjAwlLA0Ch Subject: Simultaneous read-only snapshot mount X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 13 Feb 2012 16:18:13 -0000 It's now possible/somewhat common for the ability to have two systems = can see the same disk(s) at the same time (through iSCSI or storage = systems that support dual controllers, etc).=20 Suppose system A has a filesystem mounted RW, and takes a snapshot. Can = system B access that snapshot via a read only mount, while system A = continues to read/write to that filesystem? Or more basically, is = everything needed to read a snapshot stable/unchanging enough that a = second system can read from it while the filesystem is still being = updated? -- Kevin