When a VMWare ESXi datastore runs out of space, the datastore cannot extend its capacity with iSCSI LUN Instant Allocation. Thin-provisioned iSCSI LUNs cannot map well after the space runs out. Even after extending capacity with Instant Allocation, it still cannot remap them.
Use the reclamation command to remap it that you can release the capacity, but it will still run out if you want to create another VMware ESXi datastore within the thin-provisioned iSCSI LUN. We do not recommend extending VMware ESXi datastorage with more than one thin-provisioned iSCSI LUN.