From owner-freebsd-stable@FreeBSD.ORG Wed Jun 29 09:31:12 2011 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id EDED5106566B for ; Wed, 29 Jun 2011 09:31:11 +0000 (UTC) (envelope-from petefrench@ingresso.co.uk) Received: from constantine.ingresso.co.uk (ingresso-1-pt.tunnel.tserv5.lon1.ipv6.he.net [IPv6:2001:470:1f08:176e::2]) by mx1.freebsd.org (Postfix) with ESMTP id B91B48FC08 for ; Wed, 29 Jun 2011 09:31:11 +0000 (UTC) Received: from dilbert.london-internal.ingresso.co.uk ([10.64.50.6] helo=dilbert.ingresso.co.uk) by constantine.ingresso.co.uk with esmtps (TLSv1:AES256-SHA:256) (Exim 4.73 (FreeBSD)) (envelope-from ) id 1Qbr70-0001rq-OZ; Wed, 29 Jun 2011 10:31:10 +0100 Received: from petefrench by dilbert.ingresso.co.uk with local (Exim 4.76 (FreeBSD)) (envelope-from ) id 1Qbr70-000KIT-Nl; Wed, 29 Jun 2011 10:31:10 +0100 To: freebsd-stable@freebsd.org, tsw5@duke.edu In-Reply-To: Message-Id: From: Pete French Date: Wed, 29 Jun 2011 10:31:10 +0100 Cc: Subject: Re: zfs on geli vs. geli on zfs (via zvol) X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 29 Jun 2011 09:31:12 -0000 > While zfs on geli is less complex (in the sense that geli on zfs > involves two layers of filesystems), I'm concerned as to whether > encrypting the device will somehow affect zfs' ability to detect > silent corruption, self-heal, or in any other way adversely affect > zfs' functionality. In my mind, if I use geli on zfs, then I've > got zfs directly on a device and the zvol it's providing will be > transparently gaining the benefits of zfs' various features, providing > a "safety layer" against device failure and silent corruption that > I'm not sure if geli would detect. These are very good questions - I ran ZFS on top of geli for a long time, and what I found was that when there were problems with the underlying discs, then geli would have problems and those would not be reported back to ZFS properly. I got lockups under those circumstances - when is witched to ZFS on top directly what I got were discs dropping out and ZFS properly continuing with the remaining drives. I never managed to characterise it well enougnh to file a PR I am afraid though - it only ever happened with failing hardware which made it hard to reproduce. -pete.