Magento Multiple nodes maintenance mode(exam question)

Question

An Adobe Commerce Architect is working on a multi-server horizontally scaled Adobe Commerce on-premise installation. There are three nodes up and running the Adobe Commerce installation: node A, node B, and node C. A load balancer redirects traffic to each node evenly. The Remote Storage module is enabled and set up with a private S3 bucket to sync media between the nodes. The Architect wants to connect to the cluster by SSH and enable the maintenance mode through the maintenance:enable command. Which steps should the Architect take to make sure all servers go into maintenance mode?

1. Log in to one of the running nodes and run the maintenance:enable command. All nodes will then go into maintenance mode.

2. Log in to each node individually and run the maintenance:enable command on each individual node. The nodes will go into maintenance one by one.

3. Create a custom remote storage for the var/.maintenance.flag file to get synchronized between the nodes. Then log in to one of the nodes and run the maintenance:enable command. All nodes will then go into maintenance mode.

This is an AD0-E718 Adobe Commerce Architect Master Sample Question and the correct answer provided by Adobe(no explanation) is 1. But I think 3 is correct.

Can anybody tell me why 1 is correct? Does the remote-storage module sync var/.maintenance.flag automatically, too?

Please also provide any reference/documentation if you can, thank you.

Answer 1

Kindly have a look at module-remote-storage/etc/di.xml.

    ...
    <virtualType name="fullRemoteFilesystem" type="Magento\RemoteStorage\Filesystem" />
    ...
    <type name="Magento\Framework\App\MaintenanceMode">
        <arguments>
            <argument name="filesystem" xsi:type="object">fullRemoteFilesystem</argument>
        </arguments>
    </type>

This means that when magento/module-remote-storage is enabled, the filesystem for MaintenanceMode is now also remote, hence synced up with all the nodes.