Clarify rolling upgrade fallback to restart upgrade (#42161)

Adds a note that restarting half-or-more of the master-eligible nodes means
you're no longer doing a rolling upgrade, and may need to upgrade all the
things before the cluster returns to health.
This commit is contained in:
David Turner 2019-05-16 13:36:09 -04:00
parent 226df35d96
commit 51376f98a7
1 changed files with 15 additions and 7 deletions

View File

@ -167,14 +167,22 @@ include::open-ml.asciidoc[]
During a rolling upgrade, the cluster continues to operate normally. However,
any new functionality is disabled or operates in a backward compatible mode
until all nodes in the cluster are upgraded. New functionality
becomes operational once the upgrade is complete and all nodes are running the
new version. Once that has happened, there's no way to return to operating
in a backward compatible mode. Nodes running the previous major version will
not be allowed to join the fully-updated cluster.
until all nodes in the cluster are upgraded. New functionality becomes
operational once the upgrade is complete and all nodes are running the new
version. Once that has happened, there's no way to return to operating in a
backward compatible mode. Nodes running the previous major version will not be
allowed to join the fully-updated cluster.
In the unlikely case of a network malfunction during the upgrade process that
isolates all remaining old nodes from the cluster, you must take the
old nodes offline and upgrade them to enable them to join the cluster.
isolates all remaining old nodes from the cluster, you must take the old nodes
offline and upgrade them to enable them to join the cluster.
If you stop half or more of the master-eligible nodes all at once during the
upgrade then the cluster will become unavailable, meaning that the upgrade is
no longer a _rolling_ upgrade. If this happens, you should upgrade and restart
all of the stopped master-eligible nodes to allow the cluster to form again, as
if performing a <<restart-upgrade,full-cluster restart upgrade>>. It may also
be necessary to upgrade all of the remaining old nodes before they can join the
cluster after it re-forms.
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