<div dir="ltr">if doing an upgrade from 3.10.1 to 4.0 or 4.1, will I be able to access volume without any challenge? <div><br></div><div>I am asking this because 4.0 comes with DHT2?</div><div><br></div><div><div><br></div><div><br></div></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Nov 2, 2017 at 2:26 PM, Kaushal M <span dir="ltr"><<a href="mailto:kshlmster@gmail.com" target="_blank">kshlmster@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">We're fast approaching the time for Gluster-4.0. And we would like to<br>
set out the expected upgrade strategy and try to polish it to be as<br>
user friendly as possible.<br>
<br>
We're getting this out here now, because there was quite a bit of<br>
concern and confusion regarding the upgrades between 3.x and 4.0+.<br>
<br>
---<br>
## Background<br>
<br>
Gluster-4.0 will bring a newer management daemon, GlusterD-2.0 (GD2),<br>
which is backwards incompatible with the GlusterD (GD1) in<br>
GlusterFS-3.1+. As a hybrid cluster of GD1 and GD2 cannot be<br>
established, rolling upgrades are not possible. This meant that<br>
upgrades from 3.x to 4.0 would require a volume downtime and possible<br>
client downtime.<br>
<br>
This was a cause of concern among many during the recently concluded<br>
Gluster Summit 2017.<br>
<br>
We would like to keep pains experienced by our users to a minimum, so<br>
we are trying to develop an upgrade strategy that avoids downtime as<br>
much as possible.<br>
<br>
## (Expected) Upgrade strategy from 3.x to 4.0<br>
<br>
Gluster-4.0 will ship with both GD1 and GD2.<br>
For fresh installations, only GD2 will be installed and available by default.<br>
For existing installations (upgrades) GD1 will be installed and run by<br>
default. GD2 will also be installed simultaneously, but will not run<br>
automatically.<br>
<br>
GD1 will allow rolling upgrades, and allow properly setup Gluster<br>
volumes to be upgraded to 4.0 binaries, without downtime.<br>
<br>
Once the full pool is upgraded, and all bricks and other daemons are<br>
running 4.0 binaries, migration to GD2 can happen.<br>
<br>
To migrate to GD2, all GD1 processes in the cluster need to be killed,<br>
and GD2 started instead.<br>
GD2 will not automatically form a cluster. A migration script will be<br>
provided, which will form a new GD2 cluster from the existing GD1<br>
cluster information, and migrate volume information from GD1 into GD2.<br>
<br>
Once migration is complete, GD2 will pick up the running brick and<br>
other daemon processes and continue. This will only be possible if the<br>
rolling upgrade with GD1 happened successfully and all the processes<br>
are running with 4.0 binaries.<br>
<br>
During the whole migration process, the volume would still be online<br>
for existing clients, who can still continue to work. New clients will<br>
not be possible during this time.<br>
<br>
After migration, existing clients will connect back to GD2 for<br>
updates. GD2 listens on the same port as GD1 and provides the required<br>
SunRPC programs.<br>
<br>
Once migrated to GD2, rolling upgrades to newer GD2 and Gluster<br>
versions. without volume downtime, will be possible.<br>
<br>
### FAQ and additional info<br>
<br>
#### Both GD1 and GD2? What?<br>
<br>
While both GD1 and GD2 will be shipped, the GD1 shipped will<br>
essentially be the GD1 from the last 3.x series. It will not support<br>
any of the newer storage or management features being planned for 4.0.<br>
All new features will only be available from GD2.<br>
<br>
#### How long will GD1 be shipped/maintained for?<br>
<br>
We plan to maintain GD1 in the 4.x series for at least a couple of<br>
releases, at least 1 LTM release. Current plan is to maintain it till<br>
4.2. Beyond 4.2, users will need to first upgrade from 3.x to 4.2, and<br>
then upgrade to newer releases.<br>
<br>
#### Migration script<br>
<br>
The GD1 to GD2 migration script and the required features in GD2 are<br>
being planned only for 4.1. This would technically mean most users<br>
will only be able to migrate from 3.x to 4.1. But users can still<br>
migrate from 3.x to 4.0 with GD1 and get many bug fixes and<br>
improvements. They would only be missing any new features. Users who<br>
live on the edge, should be able to the migration manually in 4.0.<br>
<br>
---<br>
<br>
Please note that the document above gives the expected upgrade<br>
strategy, and is not final, nor complete. More details will be added<br>
and steps will be expanded upon, as we move forward.<br>
<br>
To move forward, we need your participation. Please reply to this<br>
thread with any comments you have. We will try to answer and solve any<br>
questions or concerns. If there a good new ideas/suggestions, they<br>
will be integrated. If you just like it as is, let us know any way.<br>
<br>
Thanks.<br>
<br>
Kaushal and Gluster Developers.<br>
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</blockquote></div><br></div>