From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Snitzer Subject: Re: dm-multipath: Accept failed paths for multipath maps Date: Wed, 18 Dec 2013 09:08:58 -0500 Message-ID: <20131218140858.GC17730@redhat.com> References: <1387353155-7271-1-git-send-email-hare@suse.de> 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: <1387353155-7271-1-git-send-email-hare@suse.de> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: Hannes Reinecke Cc: dm-devel@redhat.com, Sean Stewart , Alasdair Kergon List-Id: dm-devel.ids On Wed, Dec 18 2013 at 2:52am -0500, Hannes Reinecke wrote: > The multipath kernel module is rejecting any map with an invalid > device. However, as the multipathd is processing the events serially > it will try to push a map with invalid devices if more than one > device failed at the same time. > So we can as well accept those maps and make sure to mark the > paths as down. Why is it so desirable to do this? Reduced latency to restore at least one valid path when a bunch of paths go down? Why can't we just rely on userspace eventually figuring out which paths are failed and pushing a valid map down? Are there favorable reports that this new behavior actually helps? Please quantify how. (As an aside, really not a fan of parse_path doing what you've suggested.. will look closer once I have more justification to do so)