From owner-freebsd-fs@freebsd.org Mon Nov 9 19:54:24 2015 Return-Path: Delivered-To: freebsd-fs@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 6C9FFA2A166 for ; Mon, 9 Nov 2015 19:54:24 +0000 (UTC) (envelope-from sean@chittenden.org) Received: from mail01.lax1.stackjet.com (mon01.lax1.stackjet.com [174.136.104.178]) (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 534FC1852 for ; Mon, 9 Nov 2015 19:54:22 +0000 (UTC) (envelope-from sean@chittenden.org) Received: from hormesis.group.on (localhost [127.0.0.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: sean@chittenden.org) by mail01.lax1.stackjet.com (Postfix) with ESMTPSA id 446FA3E8F75; Mon, 9 Nov 2015 11:54:15 -0800 (PST) Received: from hormesis.group.on ([64.125.69.70] helo=hormesis.group.on) by ASSP.nospam with SMTPS(ECDHE-RSA-AES256-SHA) (2.4.2); 9 Nov 2015 11:54:13 -0800 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 9.1 \(3096.5\)) Subject: Re: ZFS RAID 0+1 Throwing Checksum Errors From: Sean Chittenden In-Reply-To: Date: Mon, 9 Nov 2015 11:54:39 -0800 Cc: freebsd-fs@freebsd.org Content-Transfer-Encoding: quoted-printable Message-Id: References: To: Tim Gustafson X-Mailer: Apple Mail (2.3096.5) X-Assp-Version: 2.4.2(14097) on ASSP.nospam X-Assp-ID: ASSP.nospam m1-98854-01150 X-Assp-Session: 84287B690 (mail 1) X-Assp-Envelope-From: sean@chittenden.org X-Assp-Intended-For: tjg@ucsc.edu X-Assp-Intended-For: freebsd-fs@freebsd.org X-Assp-Client-TLS: yes X-Assp-Server-TLS: yes X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 09 Nov 2015 19:54:24 -0000 Tim, I've run into this a dozen or so times on servers where their power = is "dirty" (i.e. home or small offices with small servers that use ZFS). = If you plug the box into a UPS to condition the line you may find that = the checksum errors go away. It's pretty amazing to see and happens = with both SSD and spinning rust. It's not always the case, but it's a = common enough environmental problem. Report back if you try this and it = solves your problem. -sc -- Sean Chittenden sean@chittenden.org > On Nov 9, 2015, at 11:08, Tim Gustafson wrote: >=20 > I have a FreeBSD 10.1 server configured as root-on-zfs with the > following pool configuration: >=20 > NAME STATE READ WRITE CKSUM > tank ONLINE 0 0 0 > mirror-0 ONLINE 0 0 0 > gpt/zfs0 ONLINE 0 0 0 > gpt/zfs1 ONLINE 0 0 0 > mirror-1 ONLINE 0 0 0 > gpt/zfs2 ONLINE 0 0 0 > gpt/zfs3 ONLINE 0 0 0 >=20 > The disks are each 1TB Samsung 850EVO SSDs connected via an mrsas Dell > Perc raid controller configured in "RAID Disabled" mode. >=20 > I run a "zpool scrub" every weekend and every weekend the scrub finds > a handful (usually between 1 and 10) checksum errors per disk. The > scrub fixes the checksum errors, and I clear the counters and > everything seems fine. As far as I know, I do not have any corrupt or > missing data. >=20 > The server is a fairly busy web and database server, handling about 5 > million hits per day. >=20 > I'm wondering if the problem is that the scrub is calculating the > checksum for the data on gpt/zfs0, and while that's happening, some > data is updated by Apache or MySQL, and then checksum for the data on > gpt/zfs1 is calculated, which now doesn't match, and therefore the > scrub is reporting an error. Is that possible? >=20 > If that's not it, could this be a bug? Or should I be worried about > my SSDs? What additional data would be helpful for me to share to > diagnose this? >=20 > --=20 >=20 > Tim Gustafson > Technical Lead, Baskin School of Engineering > tjg@ucsc.edu > 831-459-5354 > Baskin Engineering, Room 313A > _______________________________________________ > freebsd-fs@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-fs > To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org"