I'm with a block storage vendor that works with a lot of companies migrating off VMware, and the diversity of KVM-based cloud management platforms we're seeing is fascinating. We have customers moving to OpenNebula, CloudStack, Proxmox, OpenStack, HP VME, Oracle Virtualization, and even some homegrown solutions. The common thread is that they're all looking for a storage backend that is not tied to a specific hypervisor and can deliver predictable high performance. The beauty of the KVM ecosystem is the freedom to choose the best tool for the job, and that extends to the storage layer. A good software-defined block storage solution should have the features (data migration, disaster recovery) and capabilities to make the transition away from VMware as smooth as possible.