I get a long list of all connected iSCSI targets, uncluding eventual connections to vmdks on a certain datastore.
The ones that interest us would be the following:
~ # esxcli network ip connection list | grep 3260
tcp 0 0 172.30.1.16:53293 172.30.1.201:3260 ESTABLISHED 8775 vmkiscsidtcp 0 0 172.30.1.16:62545 172.30.1.201:3260 ESTABLISHED 8775 vmkiscsidtcp 0 0 172.30.1.16:59041 172.30.1.201:3260 ESTABLISHED 8775 vmkiscsid