Confused about Kibana Task Manager index

I'm looking at getting our test and production clusters upgraded from 6.8 to 7.17 and am very confused about the .kibana_task_manager index.

Both clusters have multiple Kibana instances each with it's own kibana.index setting. E.g. the one used by the ops team has kibana.index: ".kibana_ops" and the used by the web team has kibana.index: ".kibana_web" None of them have xpack.tasks.index set.

Both clusters, currently running 6.8, have an index called .kibana_task_manager and no other indices with "task_manager" in the name. But I can't find any references in 6.8 documentation to the .kibana_task_manager index or the xpack.tasks.index.

In which version of Kibana was the index for the Kibana task manager introduced?

Why does Table 1 at Upgrade migrations | Kibana Guide [7.17] | Elastic make it seem like versions 6.0.0 through 6.4.x used an index called .kibana_task_manager_7.12.0_001? Why is there no mention of the Kibana task manager index for versions 6.5 through 7.3.x?

If kibana.index is set to unique values for each Kibana instance, should xpack.tasks.index also be set to a unique value for each Kibana instance? (We've been running for years without having xpack.tasks.index set.)

Does it matter if the Kibana task manager index is preserved during an upgrade from 6 to 7? E.g. if it's the case that a Kibana instance running 6.8 has been using .kibana_task_manager index and when I upgrade it to 7.17 I tell it to use .kibana_task_manager_ops instead, will that have any effects that anyone will notice?

@mikecote can you please shed some light on this? Thanks

Kibana Task Manager was introduced in 6.7 using its own index configured via xpack.task_manager.index. In multi tenant configurations, you should segment the task manager indices the same as .kibana indices. So if kibana.index is .kibana_ops, task manager index can be .kibana_ops_task_manager.

For 6.x versions, the usage of task manager is very light and can be dropped when upgrading from 6 to 7. You should be able to set the according xpack.task_manager.index settings prior to starting up 7.x. The set up process should create the task manager indices from there.

Thanks, that was very useful.