Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757387AbYHSVKg (ORCPT ); Tue, 19 Aug 2008 17:10:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752719AbYHSVK0 (ORCPT ); Tue, 19 Aug 2008 17:10:26 -0400 Received: from wbmler2.mail.xerox.com ([13.13.138.217]:47486 "EHLO wbmler2.mail.xerox.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752368AbYHSVK0 convert rfc822-to-8bit (ORCPT ); Tue, 19 Aug 2008 17:10:26 -0400 X-Xerox-Source-Ip: 13.151.210.15 X-Xerox-Source-Name: usa7061gw002.na.xerox.net X-Xerox-Reported-Name: USA7061GW002.na.xerox.net X-MimeOLE: Produced By Microsoft Exchange V6.5 Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT Subject: RE: [linux-pm] Power management for SCSI Date: Tue, 19 Aug 2008 17:08:58 -0400 Message-ID: <556445368AFA1C438794ABDA8901891C09532734@USA0300MS03.na.xerox.net> In-Reply-To: X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: [linux-pm] Power management for SCSI Thread-Index: Acj9hMdd4YoWXr9BQdmkLeoNIZuPgAEuqcOw References: <556445368AFA1C438794ABDA8901891C094876DA@USA0300MS03.na.xerox.net> From: "Leisner, Martin" To: "Alan Stern" Cc: "Oliver Neukum" , "Linux-pm mailing list" , "kernel list" , , , "Pavel Machek" , "Stefan Richter" X-OriginalArrivalTime: 19 Aug 2008 21:09:00.0433 (UTC) FILETIME=[CD1F1010:01C9023F] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1624 Lines: 48 Being able to drop power on the disk on demand is a useful concept. We do it, but need a number of custom patches in a number of places. When the system WANTS to access the disk, it does what is necessary to get the disk to spin up... I'm not sure dropping disk power in a control way should trigger a hot-plug event --if everyone EXPECTS it. I'm just looking for a more generic way to enable this...I'm going to be looking a 2.6.26/27 for this soon... marty > -----Original Message----- > From: Alan Stern [mailto:stern@rowland.harvard.edu] > Sent: Wednesday, August 13, 2008 4:39 PM > To: Leisner, Martin > Cc: Oliver Neukum; Linux-pm mailing list; kernel list; teheo@novell.com; > James.Bottomley@hansenpartnership.com; Pavel Machek; Stefan Richter > Subject: RE: [linux-pm] Power management for SCSI > > On Wed, 13 Aug 2008, Leisner, Martin wrote: > > > Regarding these scsi suspend patches, there's a general > > problem to drop power on disk devices on a running system. > > I discussed it in: > > > > http://www.gossamer-threads.com/lists/linux/kernel/811598 > > There's a much worse problem which that thread completely ignored: > > When you turn off power to a disk device, to the system it looks like a > hot-unplug event. Any mounted filesystems or memory mappings on that > disk will be lost. > > Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/