VMs configured with VMHA should be migrated to another storage and kept running when the primary storage is put on maintenance.

### The required feature described as a wish

When a primary storage is put on maintenance, the systemVMs are migrated to another primary storage and all user VMs are stopped. The user VMs are migrated on demand when they are manually started.

This might not be the intended behaviour for Instances on which VMHA is enabled and which are expected to by highly available. We might add a global config which will control if the Instances configured with VMHA are automatically migrated and are kept running.

Creating this issue to discuss and track this feature request.

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Discussed on https://github.com/apache/cloudstack/issues/12215
From the documentation https://docs.cloudstack.apache.org/en/4.22.0.0/adminguide/storage.html#maintenance-mode-for-primary-storage
`it will stop all guests that have any volume on that storage device.`

リンクされたプライマリストレージのメンテナンスに関するドキュメントと issue #12215 から始めてください。内容には実装ファイルやテストの名前がありません。VMHA インスタンスのグローバル設定と期待される動作（移行や VM の稼働継続を含む）を明確にし、そのうえで合意した結果を示すテストまたはドキュメントを定義してください。

索引モデルが issue の本文から書いたものです。