From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joel Becker Date: Tue, 8 Oct 2013 11:17:50 -0700 Subject: [Ocfs2-devel] [PATCH 3/7] Differentiate between no_controld and with_controld In-Reply-To: <52541AB6.4000004@suse.de> References: <20130927170748.GA11716@shrek.lan> <20130927190232.GD26517@localhost> <5246EA2E.3090405@suse.de> <20131008000054.GJ5358@localhost> <52534F2A.6060901@suse.de> <20131008004335.GL5358@localhost> <52541AB6.4000004@suse.de> Message-ID: <20131008181750.GM5358@localhost> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: ocfs2-devel@oss.oracle.com On Tue, Oct 08, 2013 at 09:46:14AM -0500, Goldwyn Rodrigues wrote: > On 10/07/2013 07:43 PM, Joel Becker wrote: > >No. It should not be on disk, and it must not be permanent. Consider a > >cluster running at version 1.2. One by one, each node is upgraded to a > >new version of ocfs2 that supports the 1.3 protocol. Each node will > >still reconnect to the cluster at 1.2 due to the third rule above. But > >when the entire cluster is taken down for maintenance, they will start > >back up at 1.3. In the future, we may even support online update to the > >new version when every node has it. > > Yes, the method I proposed works with what you mentioned and it is > not permanent. Let me elaborate on what I said. A node on mount > after setting up DLM would: > > Requests a non-blocking EX lock on the protocol version file. > If it fails, it takes a PR lock on the version file. > If it succeeds, it writes it's own version info *overwriting* what > was before and downconverts to PR lock. ie, even if there is a > higher version in the file before. > > This could be done with existing inode locks and no other locking > infrastructure needs to be added. > > This way if the first node is 1.2, the whole cluster will be 1.2 > even if a node with 1.3 joins. The first node decides what the > entire cluster will be. Later, if all nodes have upgraded to 1.3, > and the whole cluster restarts after a total cluster shutdown, the > whole cluster will start with 1.3 > > The reason I proposed a file is because this is ocfs2 specific, and > ideally should not be mixed with dlm stuff. I understood what you said, and the entire point of using the network-based DLM is to stay away from disk structures for locking. There is nothing wrong with using the DLM for DLM things. Joel -- "In the long run...we'll all be dead." -Unknown http://www.jlbec.org/ jlbec at evilplan.org