From owner-freebsd-fs@freebsd.org Fri Aug 31 03:08:59 2018 Return-Path: Delivered-To: freebsd-fs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 8CBDEF71178 for ; Fri, 31 Aug 2018 03:08:59 +0000 (UTC) (envelope-from grant@grantgray.id.au) Received: from mail.agc.net.au (mail.evps.com.au [27.121.114.102]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id E42F47E81D for ; Fri, 31 Aug 2018 03:08:58 +0000 (UTC) (envelope-from grant@grantgray.id.au) Received: from localhost (localhost [127.0.0.1]) by mail.agc.net.au (Postfix) with ESMTP id 19D714719F72; Fri, 31 Aug 2018 13:08:48 +1000 (AEST) Received: from mail.agc.net.au ([127.0.0.1]) by localhost (mail.agc.net.au [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id z60UFYnpdyzb; Fri, 31 Aug 2018 13:08:46 +1000 (AEST) Received: from localhost (localhost [127.0.0.1]) by mail.agc.net.au (Postfix) with ESMTP id 87DA54719F76; Fri, 31 Aug 2018 13:08:46 +1000 (AEST) X-Virus-Scanned: amavisd-new at mail.agc.net.au Received: from mail.agc.net.au ([127.0.0.1]) by localhost (mail.agc.net.au [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id XnjN0zJLwQiT; Fri, 31 Aug 2018 13:08:46 +1000 (AEST) Received: from mail.agc.net.au (mail.agc.net.au [27.121.114.102]) by mail.agc.net.au (Postfix) with ESMTP id 452254719F72; Fri, 31 Aug 2018 13:08:46 +1000 (AEST) Date: Fri, 31 Aug 2018 13:08:46 +1000 (AEST) From: Grant Gray To: "M. Casper Lewis" Cc: freebsd-fs Message-ID: <61612853.258505.1535684926024.JavaMail.zimbra@grantgray.id.au> In-Reply-To: <20180831030405.GZ1473@genomecenter.ucdavis.edu> References: <20180831003436.GW1473@genomecenter.ucdavis.edu> <707525919.257415.1535675999891.JavaMail.zimbra@grantgray.id.au> <20180831011607.GX1473@genomecenter.ucdavis.edu> <1121631966.257797.1535679312447.JavaMail.zimbra@grantgray.id.au> <20180831025805.GY1473@genomecenter.ucdavis.edu> <20180831030405.GZ1473@genomecenter.ucdavis.edu> Subject: Re: Failing ZFS log devices/panic MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Originating-IP: [27.121.114.102] X-Mailer: Zimbra 8.8.8_GA_1728 (ZimbraWebClient - FF62 (Linux)/8.8.8_GA_1703) Thread-Topic: Failing ZFS log devices/panic Thread-Index: zZmJfkBzzBxrnI9k3QDj3oFyx7Anmw== X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.27 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 31 Aug 2018 03:08:59 -0000 ----- On 31 Aug, 2018, at 1:04 PM, M. Casper Lewis mclewis@genomecenter.ucdavis.edu wrote: > On Thu, Aug 30, 2018 at 07:58:05PM -0700, M. Casper Lewis wrote: >> On Fri, Aug 31, 2018 at 11:35:12AM +1000, Grant Gray wrote: >> > I've currently got an issue between some HGST SATA disks and a SAS3008 HBA >> > where mixing SAS and SATA disks on the same port results in intermittent >> > I/O errors on the HGST SATA disks, but not other SAS devices. >> >> This sounds like what we are seeing, but we're not mixing SAS and SATA. > > I forgot to add: Why are the log devices showing problems and not the > cache devices? Same drives, same bus. Different access pattern, sure. > > -- > M. Casper Lewis | mclewis@ucdavis.edu > Systems Administrator | Voice: (530) 754-7978 > Genome Center | > University of California, Davis | It could be a function of synchronous write load. Log devices must be coherent. Cache devices can back-fill (I don't know how the ZFS algorithm works, but I imagine pages will continue to hit the L1 ARC before and during demotion to the L2 ARC).