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Swarm volumes formatted with LUKS version 2 under Swarm 11.1+ will not be recognized as valid Swarm volumes by versions prior to and including Swarm 11.0.x. This will result in a reformat of those volumes when rolling back to Swarm 11.0.x or earlier when aborting an upgrade attempt to a later version. The data on such volumes will be lost as a result! Follow the steps outlined in “Guidance for Upgrade Safety” below to avoid this scenario.
Swarm volumes formatted with LUKS version 1 under Swarm 11.0.x or earlier can be utilized under Swarm 12.0+ subject to guidance outlined below for upgrade/rollback scenarios.
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NOTE: the disk.encryptionType setting is not dynamic and can only be set on node / cluster restart. Once it’s determined that the upgrade to Swarm 12.0+ is successful and no rollback will be required, it’s recommended that the setting disk.encryptionType = luks1 be commented out / removed from the node / cluster configuration files, followed by a reboot of the nodes in the cluster. This will insure that all subsequent nodes / volumes added to the cluster will utilize LUKS version 2 for EAR, which is the recommended LUKS version.