VMware vSphere Update Manager Download Service (UMDS) is an optional module of vSphere Lifecycle Manager. UMDS downloads patch metadata, patch binaries, and notifications that might not otherwise be available to vSphere Lifecycle Manager.
For security reasons and deployment restrictions, vSphere, including vSphere Lifecycle Manager, might be installed in a secured network that is disconnected from other local networks and the Internet. vSphere Lifecycle Manager requires access to patch information to function properly. If you are using such an environment, you can install UMDS on a computer that has Internet access to download upgrades, patch binaries, and patch metadata, and then export the downloads to a portable media drive so that they become accessible to the vSphere Lifecycle Manager.
If the server on which vCenter Server is installed has no Internet access, but is connected to a server that has Internet access, you can automate the export process and transfer files from UMDS to the vSphere Lifecycle Manager depot by using a Web server on the machine on which UMDS is installed.
UMDS 7.0 supports patch recalls and notifications. A patch is recalled if the released patch has problems or potential issues. After you download patch data and notifications with UMDS, and export the downloads so that they become available to vSphere Lifecycle Manager, vSphere Lifecycle Manager deletes the recalled patches.
Starting with vSphere 7.0, the UMDS is available for installation only on Linux-based operating systems. Installing UMDS on a Windows machine is no longer supported. Administrator access is not a requirement for downloading patches with UMDS that runs on Linux. The machine on which you install UMDS must have Internet access.
vSphere Lifecycle Manager supports using UMDS for both images and baselines. That is, UMDS downloads updates that are packaged and distributed as bulletins, but it also works with components, which are the main software update package in vSphere 7.0