From owner-freebsd-fs@FreeBSD.ORG Fri Mar 28 21:37:01 2014 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id D30A68FC for ; Fri, 28 Mar 2014 21:37:01 +0000 (UTC) Received: from mx2.paymentallianceintl.com (mx2.paymentallianceintl.com [216.26.158.171]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (Client CN "mx2.paymentallianceintl.com", Issuer "Go Daddy Secure Certification Authority" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 778D0839 for ; Fri, 28 Mar 2014 21:37:00 +0000 (UTC) Received: from firewall.mikej.com (162-238-140-44.lightspeed.lsvlky.sbcglobal.net [162.238.140.44]) by mx2.paymentallianceintl.com (8.14.5/8.13.8) with ESMTP id s2SLaq3P081488 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=FAIL) for ; Fri, 28 Mar 2014 17:36:53 -0400 (EDT) (envelope-from mikej@mikej.com) Received: from firewall.mikej.com (localhost.mikej.com [127.0.0.1]) by firewall.mikej.com (8.14.8/8.14.8) with ESMTP id s2SLaBwh050755 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO) for ; Fri, 28 Mar 2014 17:36:51 -0400 (EDT) (envelope-from mikej@mikej.com) Received: (from www@localhost) by firewall.mikej.com (8.14.8/8.14.8/Submit) id s2SLaAiw050754; Fri, 28 Mar 2014 17:36:10 -0400 (EDT) (envelope-from mikej@mikej.com) X-Authentication-Warning: firewall.mikej.com: www set sender to mikej@mikej.com using -f To: Subject: Re: zfs l2arc warmup MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Date: Fri, 28 Mar 2014 17:35:39 -0400 From: mikej In-Reply-To: References: <20140328005911.GA30665@neutralgood.org> Message-ID: <33ff828c517307c9681c361a12cff2ee@mail.mikej.com> X-Sender: mikej@mikej.com User-Agent: Roundcube Webmail/0.6-beta X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 28 Mar 2014 21:37:01 -0000 On 2014-03-28 17:19, Dmitry Morozovsky wrote: > On Fri, 28 Mar 2014, Freddie Cash wrote: > > [snip most again] > >> Around ZFSv14-ish, the ability to import a pool with a missing ZIL >> was >> added. >> >> Remember the flow of data in ZFS: >> async write request --> TXG --> disk >> sync write request --> ZIL >> \--> TXG --> disk >> >> All sync writes are written to the pool as part of a normal async >> TXG after >> its written sync to the ZIL. And the ZIL is only ever read during >> pool >> import. > > On the other side, doesn't it put the risk on sync-dependent, like > database, > systems? > > I'm thinking not about losing the transaction, but possibly putting > your > filesystem in the middle of (database PoV) transaction, hence render > your DB > inconsistent? > > Quick googling seems to be uncertain about it... As I understand it..... (And I am always looking for an education) Any files system that honors fsync and provided the DB uses fsync should be fine. Any data loss then will only be determined by what transaction (log) capabilities the DB has. --mikej