[Gluster-users] Upgrade testing to gluster 6

[Hari Gowtham]

Hello Gluster users,

As you all aware that glusterfs-6 is out, we would like to inform you
that, we have spent a significant amount of time in testing
glusterfs-6 in upgrade scenarios. We have done upgrade testing to
glusterfs-6 from various releases like 3.12, 4.1 and 5.3.

As glusterfs-6 has got in a lot of changes, we wanted to test those portions.
There were xlators (and respective options to enable/disable them)
added and deprecated in glusterfs-6 from various versions [1].

We had to check the following upgrade scenarios for all such options
Identified in [1]:
1) option never enabled and upgraded
2) option enabled and then upgraded
3) option enabled and then disabled and then upgraded

We weren't manually able to check all the combinations for all the options.
So the options involving enabling and disabling xlators were prioritized.
The below are the result of the ones tested.

Never enabled and upgraded:
checked from 3.12, 4.1, 5.3 to 6 the upgrade works.

Enabled and upgraded:
Tested for tier which is deprecated, It is not a recommended upgrade.
As expected the volume won't be consumable and will have a few more
issues as well.
Tested with 3.12, 4.1 and 5.3 to 6 upgrade.

Enabled, disabled before upgrade.
Tested for tier with 3.12 and the upgrade went fine.

There is one common issue to note in every upgrade. The node being
upgraded is going into disconnected state. You have to flush the iptables
and the restart glusterd on all nodes to fix this.

The testing for enabling new options is still pending. The new options
won't cause as much issues as the deprecated ones so this was put at
the end of the priority list. It would be nice to get contributions
for this.

For the disable testing, tier was used as it covers most of the xlator
that was removed. And all of these tests were done on a replica 3 volume.

Note: This is only for upgrade testing of the newly added and removed
xlators. Does not involve the normal tests for the xlator.

If you have any questions, please feel free to reach us.

[1] https://docs.google.com/spreadsheets/d/1nh7T5AXaV6kc5KgILOy2pEqjzC3t_R47f1XUXSVFetI/edit?usp=sharing

Regards,
Hari and Sanju.