Scenarios:
1.) If the Datastore is shared by more than one ESXi Host:
You must rename the Datastore by using the vCenter Web Client
2.) If the Host is managed by vCenter Server:
You cannot rename the Datastore by directly accessing the Host from the VMware Host Client or using the command line.
You must rename the Datastore by using the vCenter Web Client
3.) If the Host is not managed by vCenter Server: Rename a Datastore in the VMware Host Client
4.) If the Host is not managed by vCenter Server: Rename a Datastore by using command line:
4.1) Determine the current Datastore name by running via SSH/Putty session:
df -h
4.2) Runn command to rename Datastore:
vim-cmd hostsvc/datastore/rename OldDatastoreName NewDatastoreName
4.3) Determine the new Datastore name by running via SSH/Putty session:
df -h