CONTAP-63621: Port toggle activity leads to inconsistent back end iSCSI connectivity

Issue

• Temporary loss of connectivity between clusters can result in remote drives being marked as not responding. Event log would report similar messages:

[[NodeA: intr: ctl.session.stateChanged:notice]: iSCSI CAM target layer's session state is changed to terminated for the initiator iqn.1994-09.org.freebsd:185abf42-1aba-11eb-a6fc-d039ea45ec7d (address: 10.1.2.3). Reason: no ping reply after 5 seconds.]
[[NodeA: kernel: iscsi.session.stateChanged:notice]: iSCSI session state is changed to Reconnecting for the target iqn.2016-07.com.netapp:f4d3fb1c-1aba-11eb-a87d-d039ea45eac8 (type: dr_partner, address: 10.1.1.4:65200). Reason: no ping reply after 5 seconds.]

• sysconfig -a shows an output similar to the below:
  [ slot 0: Virtual iSCSI Host Adapter 0m
  ...
  10.20: NETAPP X371_SLNGE960ATE NA52 915.4GB 520B/sect (S/N) (Failed)]
  

• sysconfig -r output is similar:

[Local broken disks
RAID Disk Device HA SHELF BAY CHAN Pool Type RPM Used (MB/blks) Phys (MB/blks)
--------- ------ ------------- ---- ---- ---- ----- -------------- --------------
not responding 0m.i2.1L21P3 0m 0 21 1 SSD N/A 63849/130764288 63857/130780672
...
not responding 0m.i1.3L27 0m 10 20 1 SSD N/A 915465/1874872832 915715/1875385008 ]