V2 Rest API is recommended for on premise applications to access Object Store. It also comes with overhead of encryption and security of using rest api. With Object Store v2, the API call is localized to the same data center as the Runtime Manager app.
But in this case requirement is to access the OS of other mule application and not the same mule application.
You can configure a Mule app to use the Object Store REST API to store and retrieve values from an object store in another Mule app.
However, Object Store v2 is not designed for app-to-app communication.

Correct answer is It is not possible to store logs for 2 years in CloudHub deployment. External log management system is required. CloudHub has a specific log retention policy, as described in the documentation: the platform stores logs of up to 100 MB per app & per worker or for up to 30 days, whichever limit is hit first. Once this limit has been reached, the oldest log information is deleted in chunks and is irretrievably lost. The recommended approach is to persist your logs to a external logging system of your choice (such as Splunk, for instance) using a log appender. Please note that this solution results in the logs no longer being stored on our platform, so any support cases you lodge will require for you to provide the appropriate logs for review and case resolution

* "Relocation of the database systems to a DMZ in the on-premises network, with Mule applications deployed to the CloudHub Shared Worker Cloud connecting only to the DMZ" is not a feasible option
* "Static IP addresses for the Mule applications deployed to the CloudHub Shared Worker Cloud, plus matching firewall rules and IP whitelisting in the on-premises network" - It is risk for sensitive data. - Even if you whitelist the database IP on your app, your app wont be able to connect to the database so this is also not a feasible option
* "An Anypoint VPC with one Dedicated Load Balancer fronting each on-premises database system, plus matching IP whitelisting in the load balancer and firewall rules in the VPC and on-premises network" Adding one VPC with a DLB for each backend system also makes no sense, is way too much work. Why would you add a LB for one system.
* Correct answer: "An Anypoint VPC connected to the on-premises network using an IPsec tunnel or AWS DirectConnect, plus matching firewall rules in the VPC and on-premises network" IPsec Tunnel You can use an IPsec tunnel with network-to-network configuration to connect your on-premises data centers to your Anypoint VPC. An IPsec VPN tunnel is generally the recommended solution for VPC to on-premises connectivity, as it provides a standardized, secure way to connect. This method also integrates well with existing IT infrastructure such as routers and appliances. Reference: https://docs.mulesoft.com/runtime-manager/vpc-connectivity-methods-concept