Introduction to Virtual Disks

A virtual disk contains two components: the virtual disk itself as it appears in a guest domain, and the virtual disk backend, which is where data is stored and where virtual I/O ends up. The virtual disk backend is exported from a service domain by the virtual disk server (vds) driver. The vds driver communicates with the virtual disk client (vdc) driver in the guest domain through the hypervisor using a logical domain channel (LDC). Finally, a virtual disk appears as /dev/[r]dsk/cXdYsZ devices in the guest domain.

The virtual disk backend can be physical or logical. Physical devices can include the following:

• Physical disk or disk logical unit number (LUN)

• Physical disk slice

Logical devices can be any of the following:

• File on a file system, such as ZFS or UFS

• Logical volume from a volume manager, such as ZFS, VxVM, or Solaris^TM Volume Manager (SVM)

• Any disk pseudo device accessible from the service domain

Figure 6–1 Virtual Disks With Logical Domains