From owner-freebsd-hackers@FreeBSD.ORG Sat Oct 5 02:39:23 2013 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTP id 4834D2FB for ; Sat, 5 Oct 2013 02:39:23 +0000 (UTC) (envelope-from subtil@gmail.com) Received: from mail-wg0-x230.google.com (mail-wg0-x230.google.com [IPv6:2a00:1450:400c:c00::230]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id DDF6C23C3 for ; Sat, 5 Oct 2013 02:39:22 +0000 (UTC) Received: by mail-wg0-f48.google.com with SMTP id n12so4981710wgh.27 for ; Fri, 04 Oct 2013 19:39:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:from:date:message-id:subject:to:content-type; bh=mtSTZR+kpF01f8YlWAxVPGJu6Wen2VqTvwzcARU0BU8=; b=0ElHnJlzVMYLnkCezT4zmFDm2MBRGqUFI2G4tbwXJSSPr5pqVeaNKl2ka5hfEIRmOV XZizSb998oWY5PZjRPSkF2eqGt2VI8GTB5D6bayLBbOI3kgANVKb9EG+DNlnAPLzv22O Qw+/EzS08Sz5E7Y4MQQ7MPEDue0vCjEovanYN+8w6Jr8uwu8lzehJWZweDV3IffaGXh5 puUcGQ/EbfUGeUDIQ6LoV9uboZ/8i7auJFRjf1b0DIuXYBbtXE8iWFFAxgGMksYVoH74 vifle+zUCt53Wl9R9iudh5UiOlNj3k3wbRHIOt41N3b4bJVOt851vjhqXSjbyFTDmwCU TSHA== X-Received: by 10.180.38.36 with SMTP id d4mr9718634wik.7.1380940761248; Fri, 04 Oct 2013 19:39:21 -0700 (PDT) MIME-Version: 1.0 Received: by 10.194.122.101 with HTTP; Fri, 4 Oct 2013 19:39:01 -0700 (PDT) From: Nuno Subtil Date: Fri, 4 Oct 2013 19:39:01 -0700 Message-ID: Subject: Staggered wake-up from standby for SATA disks To: freebsd-hackers@freebsd.org Content-Type: text/plain; charset=ISO-8859-1 X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 05 Oct 2013 02:39:23 -0000 Greetings, I have a small storage server with several SATA drives running ZFS on 9.2-RELEASE. Due to various issues (mostly dealing with noise and power consumption), the system was spec'ed with a power supply that requires spinning up the disks one by one. This problem is easily solved for boot-up by enabling power-up in standby on the drives and setting CAM_MAX_HIGHPOWER=1, which seems to work fine. I'm also interested in allowing the drives in the ZFS pool to spin down after a period of inactivity. However, it sounds like CAM_MAX_HIGHPOWER doesn't help for this scenario (or maybe I'm wrong?) --- as far as I can tell, multiple drives would be allowed to spin up from standby at the same time. Is there an equivalent mechanism for staggering wake-up from standby on SATA disks? Thanks, Nuno Subtil