For ESXi, you can modify disks as permitted by ESXi functionality. See VMware knowledge base article. You can only modify iSCSI disks on SCSI controllers with thin provisioning. And the VM cannot have VMware snapshots. If you cannot modify a hard drive as expected, please contact your System Administrator.
For SCSI disks, you cannot modify disk size and position at the same time
You can increase the size of the hard disk
|Datastore tier||Optional. Storage service level|
You cannot modify the Allocation type after the VM has been deployed
The controller type of disk
Optional. On supported hypervisors (ESXi), to force the creation of a new controller of the same type as an existing one, assign a new bus value. Access ESXi to confirm bus values.
Optional. Select an existing an existing bus number or to create a new controller, specify a new bus number. The user requests a bus number but the platform will use the bus number assigned by ESXi. When there is more than one controller, to identify the controller and bus number, the platform displays the bus number as a suffix to the controller. Access ESXi to confirm bus numbers that are not displayed
The name of the hard disk