From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nathaniel Rutman Date: Wed, 01 Apr 2009 08:13:09 -0700 Subject: [Lustre-devel] Start the MGS first? In-Reply-To: <1238011240.6090.16.camel@pc.interlinx.bc.ca> References: <49CA8A73.9080103@sun.com> <1238011240.6090.16.camel@pc.interlinx.bc.ca> Message-ID: <49D38485.3090801@sun.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: lustre-devel@lists.lustre.org Brian J. Murrell wrote: > On Wed, 2009-03-25 at 12:48 -0700, Nathaniel Rutman wrote: > >> As of Lustre 1.6, servers can be started in any order (after the initial registration at first startup). Internally, this required significant bending of our connection rules, and with a move toward ZFS becomes even more burdensome. >> So my question to the Lustre community is this: would anyone strenuously object to a startup ordering requirement that the MGS must be started before any other servers? >> This would probably be in the Lustre 3.0 timeframe. It is also likely that we will have to divorce the MGS and MDT onto separate devices -- no more "combo" MDT/MGSes. >> > > I'll ask before anyone else does... would this require the MGS be > available at any time a server (or client?) needs to start rather than > the optional behaviour (for anything but first time server starts) that > we currently enjoy? IOW, does this make the MGS a much more critical > component of the filesystem than it is currently? > yes. It's already required for client starts. What we would do is have the MDT / OST server mounts block until the MGS is up, probably with a timeout. And yes, this will be some amount less flexible than the current startup order, but we gain advantages from it - simplified import states, more centralized configuration, single-path disk access. The question is how burdensome really will this limitation be. So far I have not heard very much gnashing of teeth and rending of garments.