The iscsi initiator in FreeNAS seems to be unable to detect when a target disappears.
The initiator in my FreeNAS RC2 (have also tested stable realises) is connected to three buffalo TeraStation, when one of the buffalo's lose power or Ethernet connectivity FreeNAS continues to believe that the disk provided by the Buffalo target (now powered off) is still available.
This has made it impossible to successfully test a software raid failure on one node.
Full details here https://sourceforge.net/apps/phpbb/freenas/viewtopic.php?f=92&t=3350