# Virtual Storage Lifecycle Management API Reference

This API reference provides comprehensive information about all operation methods and data structures available through the Virtual Storage Lifecycle Management (VSLM) API.

VSLM is a Web service that runs on a vCenter Server as part of storage policy services (SPS). You use this API to connect to the VSLM endpoint and retrieve information about first class disks (FCD), which are disks not associated with a virtual machine. SPS also includes storage policy based management (SPBM) and storage management service (SMS).

First class disk (FCD), also called improved virtual disk (IVD), helps surmount the difficulty of managing virtual disks not associated with a VM. Previously it was necessary to create a dummy VM for such disk operations. For example, snapshots work on a per VM basis, and to snapshot a single VMDK rather than all VMDKs attached to a VM involved lots of configuration overhead. FCD was designed to offer full lifecycle management of virtual storage objects, independent of any VM. VSLM APIs are able to create, delete, snapshot, backup, restore, and do other lifecycle tasks on VMDK objects without requiring VM attachment.

An FCD is identified by UUID and human readable name. The UUID is globally unique and the primary identifier. The UUID remains valid even if a snapshot is taken or its FCD relocated by XvMotion.

Use cases for FCD include App Volumes, just-in-time desktops for VDI, OpenStack Cinder, Docker persistent volumes, Kubernetes nodes, and VMware Cloud Native Storage.

VSLM APIs for FCDs first appeared in vSphere 6.5. In vSphere 6.7, it became possible to backup FCD without creating a dummy VM. In vSphere 6.7 U1, vSAN added FCD support. More VSLM APIs appeared in 6.7 U2 and a few more in 6.7 U3.

## How to Navigate this API Reference Documentation

The VSLM API Reference is an HTML frameset. Click a link in the left-hand box to display a list of operation methods or data structures according to category. Once the category appears below, click an entry in the left-hand pane to display information in the right-hand pane.

To quickly find documentation for a specific operation method or data structure, start typing its name in the Quick Index field, and click on your item.