The root volume contains the /etc directory and the /home directory, which were created when the storage system was set up. The /etc directory contains configuration files that the storage system needs in order to operate. The /home directory is a default location you can use to store data.
For a V-Series system that has a disk shelf, the root volume can reside on the disk shelf (recommended) or on the third-party storage. For a V-Series system that does not have a disk shelf, the root volume resides on the third-party storage. Regardless of how many third-party storage arrays are behind the V-Series system, each V-Series system can have only one root volume.