This is fixed in 4.9 by the following PR. API allowed end users to resize but the option wasn't available through UI.
https://github.com/apache/cloudstack/pull/1595
In: /usr/share/cloudstack-management/webapps/client/scripts/storage.js
Removing:
if (jsonObj.hypervisor == "KVM" || jsonObj.hypervisor == "XenServer" || jsonObj.hypervisor == "VMware") {
if (jsonObj.state == "Ready" || jsonObj.state == "Allocated") {
allowedActions.push("resize");
}
And adding:
if (jsonObj.state == "Ready" || jsonObj.state == "Allocated") {
allowedActions.push("resize");
}
Also removing: /usr/share/cloudstack-management/webapps/client/scripts/storage.js.gz
Resolves issue