Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753958AbbFIUOW (ORCPT ); Tue, 9 Jun 2015 16:14:22 -0400 Received: from smtp2.provo.novell.com ([137.65.250.81]:60696 "EHLO smtp2.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751934AbbFIUOP (ORCPT ); Tue, 9 Jun 2015 16:14:15 -0400 Message-ID: <5577490D.4090301@suse.com> Date: Tue, 09 Jun 2015 15:14:05 -0500 From: Goldwyn Rodrigues User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: David Teigland CC: linux-kernel@vger.kernel.org, NeilBrown Subject: Re: clustered MD References: <20150609182102.GA4305@redhat.com> <55773DE1.7080107@suse.com> <20150609194505.GA17536@redhat.com> In-Reply-To: <20150609194505.GA17536@redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2086 Lines: 53 Hi David, On 06/09/2015 02:45 PM, David Teigland wrote: > On Tue, Jun 09, 2015 at 02:26:25PM -0500, Goldwyn Rodrigues wrote: >> On 06/09/2015 01:22 PM, David Teigland wrote: >>> I've just noticed the existence of clustered MD for the first time. >>> It is a major new user of the dlm, and I have some doubts about it. >>> When did this appear on the mailing list for review? >> >> It first appeared in December, 2014 on the RAID mailing list. >> http://marc.info/?l=linux-raid&m=141891941330336&w=2 > > I don't read that mailing list. Searching my archives of linux-kernel, it > has never been mentioned. I can't even find an email for the md pull > request that included it. > Is this what you are looking for? http://marc.info/?l=linux-kernel&m=142976971510061&w=2 > The merge commit states: > > - "experimental" code for managing md/raid1 across a cluster using > DLM. Code is not ready for general use and triggers a WARNING if > used. However it is looking good and mostly done and having in > mainline will help co-ordinate development. > > That falls far short of the bar for adding it to the kernel. It not only > needs to work, it needs to be reviewed and justified, usually by showing > some real world utility to warrant the potential maintenance effort. > > Why do you say it does not work? It did go through it's round of reviews on the RAID mailing list. I understand that you missed it because you are not subscribed to the raid mailing list. We do have a valid real world utility. It is to provide high-availability of RAID1 storage over the cluster. The distributed locking is required only during cases of error and superblock updates and is not required during normal operations, which makes it fast enough for usual case scenarios. What are the doubts you have about it? -- Goldwyn -- 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/