If any unused storage capacity remains on ESXi cluster members, you can expand an existing VSA cluster when it needs more storage space. You can also expand the VSA cluster after you increase physical storage capacity on the cluster members.
Use one of the following methods to increase physical storage capacity on ESXi hosts:
Install additional physical storage disks on the ESXi host. This method allows you to use a single RAID on your host or to create a separate RAID out of newly installed disks.
Replace existing storage disks with larger capacity disks on the ESXi host.
Change the host's hardware RAID level to increase space efficiency, for example, change RAID 10 to RAID 5 or RAID 6.
VMware recommends that you upgrade storage equally on all ESXi hosts that are cluster members.
Depending on whether you add storage capacity within a single RAID, or create an independent RAID, the workflows you use to modify overall storage capacity of your cluster differ. After you perform the tasks to add storage to cluster members, the VSA cluster detects additional space and can be expanded.