[
https://issues.apache.org/jira/browse/CASSANDRA-20145?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Sam Tunnicliffe updated CASSANDRA-20145:
----------------------------------------
Change Category: Operability
Complexity: Low Hanging Fruit
Fix Version/s: 5.x
Status: Open (was: Triage Needed)
> Ensure downgrade from 5.1 to 4.x is possible
> --------------------------------------------
>
> Key: CASSANDRA-20145
> URL: https://issues.apache.org/jira/browse/CASSANDRA-20145
> Project: Apache Cassandra
> Issue Type: Improvement
> Components: Local/Other
> Reporter: Sam Tunnicliffe
> Assignee: Sam Tunnicliffe
> Priority: Normal
> Fix For: 5.x
>
>
> Downgrading from current trunk to 5.0 should be unproblematic as (currently)
> there are no changes to on disk format or existing system tables.
> Rolling back to 4.x is also possible while the upgraded nodes are configured
> with storage compatibility mode {{CASSANDRA_4}}. However, this also means
> peers are unable to use messaging {{VERSION_51}}, so some of the guarantees
> around consistency and visibility of metadata changes are weakened as these
> depend on encoding metadata epochs in internode messages. Those limitations
> aside, the cluster can be operated as normal following the upgrade with
> schema and topology changes permitted. The effects of these changes persist
> through a downgrade. The downgrade requires operators to manually remove some
> directories on disk, but can be done online without taking down the entire
> cluster.
> There's one problem with this at the moment; in trunk an extra identifier is
> included in gossip digest syn messages to help guard against split brain
> scenarios when intialising a new cluster. Running with {{CASSANDRA_4}}
> compatibility currently causes the checking of this identifier to error which
> prevents the CMS being initialised (via {{nodetool cms initialize}}) during
> the 5.1 upgrade.
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
