After carving out a LUN on Equallogic SAN, the newly created volume is not showing up as a datastore on the hypervisor, even though appropriate iSCSI initiator has been added to the Access Control List for the volume.
Use vSphere client to connect to either the vCenter Server or the ESX host directly, then highlight the host you are having a problem with. Click on the Configuration tab, then select Storage Adapters in the Hardware section. In the Storage Adapters window pane select the iSCSI Software Adapter from the list, then right click on it and select Properties.
Click on the Advanced button, then scroll down until you locate the LoginTimeout field, and change the default value of 5 (seconds) to 60 (seconds). Then click on the OK button.
Repeat steps outlined above on all of your hosts (if necessary) the under Configuration, Storage, click on Rescan All, to rescan all the Datastores. The one you were having an issue with should now show up the the list.