In order to help easily migrate from NSX for vSphere to NSX-T, with minimal downtime, the latest release of VMware NSX-T 3.0 introduces Maintenance Mode to NSX-T Migration Coordinator (a tool that has been built into NSX-T since the 2.4 release). The Migration Coordinator tool is designed to run in-place on the same hardware that is running NSX for vSphere, and swap out NSX for vSphere bits with NSX-T.
This blog post is a follow up to the previous blog, Migration from VMware NSX for vSphere to NSX-T, which covers Migration Coordinator. For more details on the Migration Process, please check out the previous blog. This blog focuses on the Maintenance Mode feature which is part of the NSX-T 3.0 release.