Navigate to Storage and highlight the Volume you just created and Select create zVol

Enter a Volume name and the size, if using GB be sure to enter the g after the number.  Select Add zvol

Navigate to Services on the top bar and turn on iSCSI by clicking on the Toggle

Click on the Wrench next to iSCSI to enter the iSCSI Settings

Select Portals and Add Portal

Give the Portal a comment and leave the IP at 0.0.0.0 which means it will communicate with all IPs

Select Initiators and select Add Initiator

We could lock this down but for the lab environment I will leave at ALL and ALL and click OK

Select Authorised Access and select Add Authorised Access

Enter a Username and Password details ( I kept them simple for the lab)

Select Targets and Add Target

Enter Relevant details i.e Target Name and Alias and use Drop down menu on the Portal Group ID and Initiator Group ID just created

Select Extents and Add Extent

Enter a name for the Extent and Select Device from the Extent Type options.  Select the Volume you want from the Device window and click OK

Select Associated Targets and Add Target / Extent

Give the Extent a LUN ID and select the Target and Extent from the drop downs and click OK

So from here we can map this back to vSphere or Windows.  As a quick test, I will map it to a Windows Box.

Bring up the iSCSI Initiator and enter the IP of the FreeNAS Box – click Quick Connect

Select Done

Now if we go into Computer Management / Disk Management we should see Windows wanting to Add the Drive

Select OK and add Volumes as necessary

Make sure you can Write files to the New Drive