From owner-freebsd-hardware@freebsd.org Thu Aug 10 15:23:15 2017 Return-Path: Delivered-To: freebsd-hardware@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 07A0DDD5839 for ; Thu, 10 Aug 2017 15:23:15 +0000 (UTC) (envelope-from frank2@fjl.co.uk) Received: from bs1.fjl.org.uk (bs1.fjl.org.uk [84.45.41.196]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "bs1.fjl.org.uk", Issuer "bs1.fjl.org.uk" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id A1C3864972 for ; Thu, 10 Aug 2017 15:23:13 +0000 (UTC) (envelope-from frank2@fjl.co.uk) Received: from [192.168.1.35] (host86-191-18-76.range86-191.btcentralplus.com [86.191.18.76]) (authenticated bits=0) by bs1.fjl.org.uk (8.14.4/8.14.4) with ESMTP id v7AFMwNO020008 for ; Thu, 10 Aug 2017 16:23:00 +0100 (BST) (envelope-from frank2@fjl.co.uk) Subject: Re: Do I need SAS drives?.. To: freebsd-hardware@freebsd.org References: <4DFBCE11-913A-4FC9-937D-463B4D49816C@aldan.algebra.com> From: Frank Leonhardt Message-ID: <25450400-4ba2-76d4-605c-fce37c1c905b@fjl.co.uk> Date: Thu, 10 Aug 2017 16:22:59 +0100 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Content-Filtered-By: Mailman/MimeDel 2.1.23 X-BeenThere: freebsd-hardware@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: General discussion of FreeBSD hardware List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 10 Aug 2017 15:23:15 -0000 On 10/08/2017 15:01, Alan Somers wrote: > Really interesting answer Alan, thank you very much ! >> Slightly off-topic but I take this opportunity, >> how do you check SAS drives health ? >> I personally cron a background long test every 2 weeks (using smartmontools). >> I did not experience SAS drive error yet, so not sure how this behaves. >> Does the drive reports to FreeBSD when its read or write error rate cross >> a threshold (so that we can replace it before it fails) ? >> Or perhaps smartd will do ? >> >> As an example below a SAS error counter log returned by smartctl : >> Errors Corrected by Total Correction Gigabytes Total >> ECC rereads/ errors algorithm processed uncorrected >> fast | delayed rewrites corrected invocations [10^9 bytes] errors >> read: 0 49 0 49 233662 73743.588 0 >> write: 0 3 0 3 83996 9118.895 0 >> verify: 0 0 0 0 28712 0.000 0 >> >> Thank you ! >> >> Ben > smartmontools is probably the best way to read SAS error logs. > Interpreting them can be hard, though. The Backblaze blog is probably > the best place to get current advice. But the easiest thing to do is > certainly to wait until something fails hard. With ZFS, you can have > up to 3 drives' worth of redundancy, and hotspares too. I concur with Alan. Trying to predict drive failure is a mug's game. Very through research (e.g. Google, 2007) has shown it's a waste of time trying. With ZFS (or geom mirror) a drive will be "failed" as soon as there's a problem and you can get notification using a cron job that sends an email if the output of zpool status (or gmirror status ) contains "DEGRADED". That said, I've found it useful to use smartctl to pick up when a drive is overheating, usually due to fan failure. You might also find the new (11.0+?) sesutil handy to monitor components on a SAS expander IF YOU HAVE ONE. Things like fans and temperature sensors are readable this way. Regards, Frank.