From owner-freebsd-questions@freebsd.org Sat Dec 31 00:50:08 2016 Return-Path: Delivered-To: freebsd-questions@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 6DB76C9693C for ; Sat, 31 Dec 2016 00:50:08 +0000 (UTC) (envelope-from mike@tela.com) Received: from spider3.tela.com (smtp3.tela.com [208.90.22.69]) (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 4F20714E4 for ; Sat, 31 Dec 2016 00:50:07 +0000 (UTC) (envelope-from mike@tela.com) Received: by spider3.tela.com (Postfix, from userid 103) id 4B7C934A8AD; Fri, 30 Dec 2016 18:38:02 -0600 (CST) DKIM-Filter: OpenDKIM Filter v2.10.3 spider3.tela.com 4B7C934A8AD DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=tela.com; s=comtela1601; t=1483144682; bh=N0nB/pha1eJNO9fmtudpYMQVQ23DScFcaO2/66xwwgk=; h=Date:From:To:Subject:References:In-Reply-To; z=Date:=20Fri,=2030=20Dec=202016=2018:38:02=20-0600|From:=20Mike=20 Selner=20|To:=20freebsd-questions@freebsd.org|Subje ct:=20Re:=20ZFS=20crash=20on=20mountroot=20after=20removal=20of=20 slog=20device|References:=20<20161222012310.GA59045@spider3.tela.c om>|In-Reply-To:=20<20161222012310.GA59045@spider3.tela.com>; b=ncLcraa/EJeMmF8O2ltHEIu4qIuWfYsK8R6SC5dgFURi47bvfjxWPncZxM8Jsllv/ n2nRjVo9266fMsn1GMrb2ppjepXmJhe8TUP6mlgl4FgW3fi4ROYpNPHrXs9XXtKY/r vo815dRsygu2mmWXbo8k92s9Q6iMJRMSDqB5HZ/Q= Date: Fri, 30 Dec 2016 18:38:02 -0600 From: Mike Selner To: freebsd-questions@freebsd.org Subject: Re: ZFS crash on mountroot after removal of slog device Message-ID: <20161231003801.GC43835@spider3.tela.com> References: <20161222012310.GA59045@spider3.tela.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161222012310.GA59045@spider3.tela.com> X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 31 Dec 2016 00:50:08 -0000 Update - no replies on this, don't know if anyone has suggestions. I checked the history on the original pool and it was set up on 9.3 with two mirrored devices ada0p3 and ada1p3. A few months later I added an identically sized vdev with mirrored devices ada2p3 and ada3p3. I built a new system with a similar setup including slog on ssd and shut down, unplugged the slog device to simulate a failure and rebooted. The system came up fine and zpool status showed a missing log device. I was able to remove the device with zpool remove root devicename. No crashes. So I'm confident that zpool remove slog device should work. Next I added a "znew" pool to the original system (running off a memstick). I did a zfs send -R zpool@snapshot into zfs recv -d znew. Then I made znew/ROOT/default the bootable FS & was able to boot and run off of znew. I think this tells me that the problem on the original pool is some type of corruption but the data was recoverable with zfs send. At no point in this adventure did I have the opportunity to do any kind of rollback, so I'm not sure what else I could have done. Still, I'm concerned that a device failure could render a production server unusable. Full details at https://forums.freebsd.org/threads/59006/. Thanks for any suggestions on recovering a zpool that crashes when mounting root.