if doing an upgrade from 3.10.1 to 4.0 or 4.1, will I be able to access volume without any challenge?
I am asking this because 4.0 comes with DHT2? On Thu, Nov 2, 2017 at 2:26 PM, Kaushal M <[email protected]> wrote: > We're fast approaching the time for Gluster-4.0. And we would like to > set out the expected upgrade strategy and try to polish it to be as > user friendly as possible. > > We're getting this out here now, because there was quite a bit of > concern and confusion regarding the upgrades between 3.x and 4.0+. > > --- > ## Background > > Gluster-4.0 will bring a newer management daemon, GlusterD-2.0 (GD2), > which is backwards incompatible with the GlusterD (GD1) in > GlusterFS-3.1+. As a hybrid cluster of GD1 and GD2 cannot be > established, rolling upgrades are not possible. This meant that > upgrades from 3.x to 4.0 would require a volume downtime and possible > client downtime. > > This was a cause of concern among many during the recently concluded > Gluster Summit 2017. > > We would like to keep pains experienced by our users to a minimum, so > we are trying to develop an upgrade strategy that avoids downtime as > much as possible. > > ## (Expected) Upgrade strategy from 3.x to 4.0 > > Gluster-4.0 will ship with both GD1 and GD2. > For fresh installations, only GD2 will be installed and available by > default. > For existing installations (upgrades) GD1 will be installed and run by > default. GD2 will also be installed simultaneously, but will not run > automatically. > > GD1 will allow rolling upgrades, and allow properly setup Gluster > volumes to be upgraded to 4.0 binaries, without downtime. > > Once the full pool is upgraded, and all bricks and other daemons are > running 4.0 binaries, migration to GD2 can happen. > > To migrate to GD2, all GD1 processes in the cluster need to be killed, > and GD2 started instead. > GD2 will not automatically form a cluster. A migration script will be > provided, which will form a new GD2 cluster from the existing GD1 > cluster information, and migrate volume information from GD1 into GD2. > > Once migration is complete, GD2 will pick up the running brick and > other daemon processes and continue. This will only be possible if the > rolling upgrade with GD1 happened successfully and all the processes > are running with 4.0 binaries. > > During the whole migration process, the volume would still be online > for existing clients, who can still continue to work. New clients will > not be possible during this time. > > After migration, existing clients will connect back to GD2 for > updates. GD2 listens on the same port as GD1 and provides the required > SunRPC programs. > > Once migrated to GD2, rolling upgrades to newer GD2 and Gluster > versions. without volume downtime, will be possible. > > ### FAQ and additional info > > #### Both GD1 and GD2? What? > > While both GD1 and GD2 will be shipped, the GD1 shipped will > essentially be the GD1 from the last 3.x series. It will not support > any of the newer storage or management features being planned for 4.0. > All new features will only be available from GD2. > > #### How long will GD1 be shipped/maintained for? > > We plan to maintain GD1 in the 4.x series for at least a couple of > releases, at least 1 LTM release. Current plan is to maintain it till > 4.2. Beyond 4.2, users will need to first upgrade from 3.x to 4.2, and > then upgrade to newer releases. > > #### Migration script > > The GD1 to GD2 migration script and the required features in GD2 are > being planned only for 4.1. This would technically mean most users > will only be able to migrate from 3.x to 4.1. But users can still > migrate from 3.x to 4.0 with GD1 and get many bug fixes and > improvements. They would only be missing any new features. Users who > live on the edge, should be able to the migration manually in 4.0. > > --- > > Please note that the document above gives the expected upgrade > strategy, and is not final, nor complete. More details will be added > and steps will be expanded upon, as we move forward. > > To move forward, we need your participation. Please reply to this > thread with any comments you have. We will try to answer and solve any > questions or concerns. If there a good new ideas/suggestions, they > will be integrated. If you just like it as is, let us know any way. > > Thanks. > > Kaushal and Gluster Developers. > _______________________________________________ > Gluster-users mailing list > [email protected] > http://lists.gluster.org/mailman/listinfo/gluster-users >
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