From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joe Thornber Subject: Re: Hibernate/Resume and dm-cache, dm-writeboost... Date: Tue, 30 Dec 2014 10:32:29 +0000 Message-ID: <20141230103228.GA31888@debian> References: <549B0785.3060807@rolffokkens.nl> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <549B0785.3060807@rolffokkens.nl> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: device-mapper development Cc: Kent Overstreet , Mathijs Kwik List-Id: dm-devel.ids On Wed, Dec 24, 2014 at 07:35:49PM +0100, Rolf Fokkens wrote: > Hi all, > > On the linux-bcache mailing list the potential issue was brought up > about writes to backing or caching device after bringing up devices > in initramdisk, but prior to an actual resume. The actual issue is > that there should be no writes between hibernation and resume: > > http://www.spinics.net/lists/linux-bcache/msg02692.html > > If this is an issue for bcache, I can imagine it also is for other > caching solutions like dm-cache and dm-writeboost. I'm not an expert > on this, but from my user perspective it seems somewhat concerning > (for both bcache and the DM caching solutions) and an expert view on > this might be needed. Thanks for bringing this to our attention. I think dm-cache provides the neccessary tools to do this; either setting the migration threshold to zero, or switch to write through mode for the duration of the hibernate. But atm this would need to be triggered from userland. I need to look at hibernate more. - Joe