From owner-freebsd-scsi@freebsd.org Fri Dec 4 09:13:32 2015 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 7A24DA3FBE7 for ; Fri, 4 Dec 2015 09:13:32 +0000 (UTC) (envelope-from kevin.bowling@kev009.com) Received: from mail-yk0-x229.google.com (mail-yk0-x229.google.com [IPv6:2607:f8b0:4002:c07::229]) (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 34EE91558 for ; Fri, 4 Dec 2015 09:13:32 +0000 (UTC) (envelope-from kevin.bowling@kev009.com) Received: by ykba77 with SMTP id a77so116991942ykb.2 for ; Fri, 04 Dec 2015 01:13:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kev009.com; s=google; h=mime-version:date:message-id:subject:from:to:cc:content-type; bh=KkDFmPafD30SO94KWd4yZg0JRyptK86gzm1oSvEfuOA=; b=HW7yxRzmbxAqapf87IU/oOr8erjzAxw8loOQZynAvoq0RkcFKR8sXYTNbh2mnxokCA 51Fto5ogdpwHNsqv+BtdKTZHwTi6/rOlk2Oib5Q9VhbX8V4ly9oC4O/bYE8844JJknQy eyex8NdwhbGsHL6kqN+cvG1r4pWKj/Tz8c98Y= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:date:message-id:subject:from:to:cc :content-type; bh=KkDFmPafD30SO94KWd4yZg0JRyptK86gzm1oSvEfuOA=; b=UDVKe5x8rrKSxWvTj5iCZlObX0ZGEMm5QWXV3k5kR42nKwv0mvfTJWsyhS2Dnktv/b rwaJvnHTq98K0yP0TPZGplqKHbfwVfyGLFQDh7ZlK9277g5QBCGz6At4qcdkjsazdAnW Rzi8lqJmaoRG4evLJdJqFvveg1aRXUTtoyrligKu4FWY2tJ0A0ZGkh2AwRG6eE6LWvLE Vp02ID4zMYC147pGczdPwqyUGkdQTzfeVU6nUkHcC+kj/59XeLQXhywujVsBGQZO6yBS 3D+zmjHxX+T5idnovtoY74uGboLddKm5K3cTg0ILEqHQjbI+pyjQllh0jSclQkgI6S/n cpJg== X-Gm-Message-State: ALoCoQngXA+aHOfMP1VAPK7lR7d6UD1LS9n9Qcgp/PpqbK4x1jWtZXjiEI9XhvbXJkZrq50GtJ53 MIME-Version: 1.0 X-Received: by 10.129.49.6 with SMTP id x6mr9984476ywx.59.1449220411449; Fri, 04 Dec 2015 01:13:31 -0800 (PST) Received: by 10.37.13.147 with HTTP; Fri, 4 Dec 2015 01:13:31 -0800 (PST) Date: Fri, 4 Dec 2015 02:13:31 -0700 Message-ID: Subject: Accessing static drive info w/o ATA identify and lockup with camcontrol identify From: Kevin Bowling To: freebsd-scsi@freebsd.org Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.20 X-BeenThere: freebsd-scsi@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: SCSI subsystem List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 04 Dec 2015 09:13:32 -0000 This email is two parts that are somewhat related #1 I have seen two cases where camcontrol identify can lock up a box. On a system I have control over, I can downgrade the LSI firmware on a machine with a SAS1008 and dispatch camcontrol identify to all the disks in a loop. I/O on the system will hang silently in the background fairly quickly, but there is no indication as to how low the freeze is. I'm not sure if it's kernel side or firmware. You wont initially notice it, but then zfs will hang waiting for txgs and the machine is out to lunch. On this box, if I upgrade firmware I don't see the lockup. I got another report where a user is seeing this on AHCI https://github.com/saltstack/salt/issues/28518 with the same cause and effect. This user's lockup raises the spidy senses and makes me want to dig deeper and make sure there isn't a loose end in kernel. #2 This all came about because I want to poll device information like disk model, serial number, speeds, etc. Common use cases would be configuration management systems and inventory databases. Issuing an ATA identify seems a bit much and could trigger unwanted HW errata like above. I'm wondering if it would be better to cache the data on interface change in sysctls or something. The data is static, read only, but we need to account for disk swaps. Regards, Kevin