Change the policy at which the hosts connecting to the storage (Multipathing policy)
Right click on the datastore on that storage-> properties -> Manage Paths
U have three options: 1- Round Robin: which will randomize connections to each one of the 8 paths (one a time and hence u'll see the 8 are active)
2-) Fixed: which will make the paths to the datastore fixed till one is down, it'll be replaced.
3-) Last recently used: From its name, it'll use last one used to connect to the datastore.
Check this link for further explanation:
VMware KB: Multipathing policies in ESXi 5.x and ESXi/ESX 4.x
VMware KB: Modifying path information for ESXi/ESX hosts
Hope it really helps.. 