古いSnapshotでノードがリバートされない

ルートボリュームSnapshotがノードのリバートを妨げている：
> revert_to 9.x
Newer snapshots on volume "vol0" that must be deleted prior to reverting:
hourly.0

Snapshotの削除が次のエラーで失敗します。
::*> snapshot prepare-for-revert -node <node-1>
Warning: This command will delete all Snapshot copies that have the format
used by the current version of ONTAP. It will fail if Snapshot copy
policies are enabled, or if Snapshot copies have an owner. Continue?
{y|n}: y
Error: command failed: Internal error occurred on node "node-1" in
cluster "cluster-1". Details: (database mccDRCOperation is not open)