From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tim Small Subject: AHCI link power management and surprise hotplug Date: Thu, 19 Mar 2009 11:03:37 +0000 Message-ID: <49C22689.9050005@buttersideup.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from relay1.allsecurenet.com ([66.111.57.92]:39920 "EHLO relay1.allsecurenet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751204AbZCSLdx (ORCPT ); Thu, 19 Mar 2009 07:33:53 -0400 Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: linux-ide@vger.kernel.org Cc: kristen.c.accardi@intel.com Hello, I've been configuring SATA link power management (Documentation/scsi/link_power_management_policy.txt) on servers which use software RAID for a while, but I happened to come across this in the ICH9 datasheet: " For reliable device removal notification while in AHCI operation without the use of interlock switches (surprise removal), interface power management should be disabled for the associated port. See Section 7.3.1 of the AHCI Specification for more information. " Is this actually an issue from a libata point of view? Do I need to ensure that link power management is disabled prior to hot-removal, and if so, I suppose link_power_management_policy.txt should be updated to reflect this... On a related topic, is there any way to do anything other than "surprise" removal with libata? It'd be nice to put a drive to sleep (e.g. with "hdparm -Y"), and ensure that nothing comes along and causes the drive to be reset and spin the drive attached to that SATA port back up prior to a removal and reinsertion. I'm assuming that physically unplugging a non-spinning drive is preferable to unplugging a spinning one from a drive longevity point of view (I use SATA drives as removable backup medium in some cases). Cheers, Tim.