From mboxrd@z Thu Jan 1 00:00:00 1970 References: From: Zdenek Kabelac Message-ID: <3ebc32f0-963e-9d18-baf7-03a762ec12f5@redhat.com> Date: Fri, 31 May 2019 10:38:18 +0200 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US Content-Transfer-Encoding: quoted-printable Subject: Re: [linux-lvm] A couple of questions on locking library Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="windows-1252"; format="flowed" To: LVM general discussion and development , Shawn Guo , David Teigland Dne 31. 05. 19 v 9:13 Shawn Guo napsal(a): > Hi David, Zdenek, >=20 > Comparing to stable-2.02 branch, I noticed that there are significant > changes around locking infrastructure on master branch. I have a > couple of questions regarding to these changes. >=20 > 1. I see External Locking support was removed as part of clvmd > removal. What's the reason for dropping External Locking support? I'm > asking because we are investigating the possibility to use hardware > assisted locking for cluster, in form of External Locking extension. >=20 > 2. It seems there have never been real support for LV (Logic Volume) > locking. On stable-2.02 branch, the LV locking interface is used as > activation path instead of real locking on LV. And on master branch, > activation path gets separated off from locking infrastructure. As > the result, the LV interface is dropped completely from locking > infrastructure. My question is why there have never been LV locking > support. Is the LV locking support an invalid requirement at all? Or > it's just because no one cares about it enough to add the support? >=20 > Thanks for your time, and appreciate any comment you would give here. With stable-2.02 branch - there was always per-LV locking. The 'state' of the LV was matching state of lock. http://people.redhat.com/agk/talks/CLVM-UKUUG2007/ See the 'DLM =E2=80=93 Distributed Lock Manager' The lock however was always took only for top-level LV - never for those=20 component LVs. -- There is however believe, that users no longer use volumes with shared=20 activation (active at one time on multiple hosts) - so lvm2 is now being mo= ved transformed to theoretically less complex locking scheme... Regards Zdenek