VMware has defended its decision to stop offering public downloads of its Virtual Disk Development Kit, a software tool that helps developers build applications for virtual machine backup and migration. The company, now owned by Broadcom, quietly removed the download pages in late August without announcing the change or explaining why. The move has disrupted migration projects and drawn criticism from smaller consultancies and open-source developers who relied on free access to the toolkit.
The Virtual Disk Development Kit is a set of libraries and utilities that lets software developers create applications capable of accessing and manipulating virtual disks, according to a Broadcom technical document. The toolkit provides programming interfaces for backup and recovery, cloning, and other operations on virtual disks. Because of these capabilities, VMware's competitors incorporated the toolkit into their migration tools—Nutanix's Move product requires a Virtual Disk Development Kit library to function, Red Hat recommends using it for migrations, and ShapeBlue notes that the virt-v2v engine underlying most VMware-to-KVM conversion work supports the toolkit as an input transport. The withdrawal hit unevenly: large backup vendors with partner relationships have someone to call, but a three-person migration consultancy, an open-source project, or a customer converting their own workloads faces a forum post and a 404 error, ShapeBlue wrote.
VMware told The Register that access to the toolkit remains available through select technology alliance partners for its licensed use case, which has always been backup and recovery, and customers needing those capabilities can choose from the many approved solutions already available from these partners. A company spokesperson added that the toolkit isn't a customer entitlement but rather a software development kit covered by its own developer license that was never included with a Broadcom software purchase. VMware's position is therefore that users shouldn't expect they can use the toolkit, and that migrations represent an unlicensed use case for the tool—which stays available as part of products from technology alliance partner members.
The decision comes as VMware's changed licensing policies have prompted some users to either consider reducing their reliance on its products or shift to a rival platform, as was the case at VMware channel partner Rackspace. The toolkit has been available for download for years, and VMware can't have been unaware of how its rivals used the software to make migrations easier, making it difficult to avoid the conclusion that this represents a defensive move by VMware given it allowed downloads for years. Yet moving virtual machines is among the easier parts of a virtualization migration project—rebuilding or replacing the entirety of a virtualized environment across networks, security, and storage is the hard part, and VMware knows it, which is why it offers a site recovery tool that doubles as a migration utility. Removing easy access to the toolkit therefore doesn't change much for those planning a move away from VMware. The technical barrier remains low enough that the strategic calculus for organizations evaluating alternatives will likely hinge on broader factors—licensing costs, vendor lock-in concerns, and long-term platform strategy—rather than the availability of a single migration utility.