From owner-freebsd-scsi@freebsd.org Thu Aug 10 14:01:49 2017 Return-Path: Delivered-To: freebsd-scsi@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 03535DD3AC9; Thu, 10 Aug 2017 14:01:49 +0000 (UTC) (envelope-from asomers@gmail.com) Received: from mail-wm0-x236.google.com (mail-wm0-x236.google.com [IPv6:2a00:1450:400c:c09::236]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 8D4B6215A; Thu, 10 Aug 2017 14:01:48 +0000 (UTC) (envelope-from asomers@gmail.com) Received: by mail-wm0-x236.google.com with SMTP id f15so23400468wmg.1; Thu, 10 Aug 2017 07:01:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:sender:in-reply-to:references:from:date:message-id :subject:to:cc; bh=Z7bKJx5yIn2Q8yVVDmcOhwU4mPEDxWqePFVlFI0CfL0=; b=fpv7yE6o23ctmSUYEsDpDcY3BcbpIQWgXQfyU20v4EuKRxgb9PbWkC7tKDVi/aghdj m3X8hUbIXqg5yOPZdaIL9S6ERpZRjc6iG8L9WLynZI9soqYrPnRubGjQg+IqbFWSb4jC RQJQtDe1/SL72IPErfeLcX7sUYFx2QeiZaUwtsIct1NNH+I0OhoOAR6vfiBjQsLwQn3Z Xa2+zDxY1DbkFMuLCYTyelm0VE1/atPJkM6AYwcP6Px8yyTvDFoQFOjtRKH9AoLMXp9o AYcSBI9uWS+sy371tZ7SKrfNSrXLWupbIvh10T9CGT7qocQ+GDlPUf9lWkPOGJcXGyHN 3HjQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:sender:in-reply-to:references:from :date:message-id:subject:to:cc; bh=Z7bKJx5yIn2Q8yVVDmcOhwU4mPEDxWqePFVlFI0CfL0=; b=gubTab91Sa7Pzv7gFWqeCouHvXc9A4HXUitTaf4tBfGehm3CC+TCndBB2P6LIoF3jZ UuaFVHA476Nv855kpuJjL7NdqGqnaMkuAqTKruAyXz+wYArtafF4vn50mEoOEs1o4Vr7 kc4MaM62MhjnEEbJN1IQFVEf3SlTHJTv7WW1UL2wEwhbyRKKx8ilftHJf6bgWhlxOdK6 5do8vfqYL6BvHWfAEOUNgAAfzvhIU7F9lDZ1vKMwhn87SZ8siZf0xub97bfsfaaYeL6t ZCaV0EE9qHMvOr3O243cDQzU4L5JNuzl38tExhQ6U43juM+pEwhSKOWkgqcASU3pfnHG 6n+A== X-Gm-Message-State: AHYfb5jDb5XFCT9C6tTQrDQKxbplH0vjxOGdn33sOwgzWlGyc9jlznHt TZXQKqF0rVwlwa+VS2iua1CtN33YxQ== X-Received: by 10.28.170.18 with SMTP id t18mr7603839wme.6.1502373706889; Thu, 10 Aug 2017 07:01:46 -0700 (PDT) MIME-Version: 1.0 Sender: asomers@gmail.com Received: by 10.28.208.3 with HTTP; Thu, 10 Aug 2017 07:01:46 -0700 (PDT) In-Reply-To: References: <4DFBCE11-913A-4FC9-937D-463B4D49816C@aldan.algebra.com> From: Alan Somers Date: Thu, 10 Aug 2017 08:01:46 -0600 X-Google-Sender-Auth: V3Ta4p3yRSRdEMKZCbwrv6N80-I Message-ID: Subject: Re: Do I need SAS drives?.. To: Ben RUBSON Cc: FreeBSD-scsi , freebsd-hardware@freebsd.org Content-Type: text/plain; charset="UTF-8" X-BeenThere: freebsd-scsi@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: SCSI subsystem List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 10 Aug 2017 14:01:49 -0000 On Thu, Aug 10, 2017 at 7:44 AM, Ben RUBSON wrote: >> On 09 Aug 2017, at 17:59, Alan Somers wrote: >> >> 3) SAS drives have a lot of fancy features that you may not need or >> care about. For example, (...) their error >> reporting capabilities are more sophisticated than SMART > > 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. -Alan