From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Jones Subject: Re: [linux-pm] Dangers of touching disk between suspend and resume Date: Thu, 30 Nov 2006 17:17:47 -0500 Message-ID: <1164925067.6031.29.camel@localhost.localdomain> References: <1164727307.26898.12.camel@systems03.lan.brontes3d.com> <20061128163757.GM14640@suse.de> <1164916843.6031.9.camel@localhost.localdomain> <20061130201311.GK2227@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20061130201311.GK2227@suse.de> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: suspend-devel-bounces@lists.sourceforge.net Errors-To: suspend-devel-bounces@lists.sourceforge.net To: Stefan Seyfried Cc: suspend-devel@lists.sourceforge.net, linux-pm@osdl.org, Alan Stern List-Id: linux-pm@vger.kernel.org On Thu, Nov 30, 2006 at 03:00:43PM -0500, I wrote: > On Tue, 2006-11-28 at 17:37 +0100, Stefan Seyfried wrote: > > > So it is a good idea to tell the engineer to do "mkswap" on the swap > > partition before putting the disk into the replacement hardware. > > Ugh, no it's not. You really want the UUID on the swap area to remain > the same. In response, on Thu, 2006-11-30 at 21:13 +0100, Stefan Seyfried wrote: > Well, but the system won't care because it won't resume? > Or am i missing something? And On Thu, 2006-11-30 at 15:42 -0500, Daniel Drake wrote: > Why? > > [not questioning your reasoning, this is coming from someone who knows > very little about swap structure and what the UUID is used for] You want to get rid of the resume metadata from it, but you don't want to create a new swap structure. Normally it's not a problem, but in some environments, such as with shared-storage like in a SAN[1], we need to be able to identify that a swap device is really the one we mean to be activating; the UUID is one of the best pieces of data we've got. So you don't want to start over with a new swap partition, you want to clear the resume data only. Granted, I think most distros, if not all, and all the standard tools totally muck up swap on shared storage right now[0]. But that's no reason to advocate such a bad habit. For FC/RHEL making this work right is at least on my TODO list for the relatively near future. [0] "swapon -a" activates everything it finds, and that's what most distros do during boot. If you can see other machines' swap devices, that's bad. [1] If you hate that example, another with the same problem is when you're running a virtual machine which has its own physical disk partitions, i.e. vmware with /dev/sdb as its disk. -- Peter ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV