A feature called Acropolis Block Services (ABS) was released with Acropolis OS 4.7 (AOS). It allows DFS resources to be exposed directly to a virtualized guest OS or physical hosts using the iSCSI protocol. This capability enables support for several use cases such as shared storage for Oracle RAC and other applications that require shared storage.
The XC Series Nutanix storage configuration for ABS is handled through a construct called a volume group (VG). A VG is a collection of volumes commonly known as virtual disks (vdisks). ABS presents these vdisks to virtual machines and physical servers using iSCSI protocol. Multiple hosts can share the vdisks associated with a VG as shown in Figure 3. This is very helpful for shared storage use cases such as Oracle RAC or Windows server clustering.