Datastore connectivity issues

We have a shared datastore to provide global catalogs to our various ORG's in the vCloud.  For whatever reason several ESX hosts across mulitple clusters were reporting APD (all path's down) when trying to connect to this VNX NFS Export.  After putting those hosts into maintenance mode, everything seemed happy again.   We did quite a bit of digging, it turned out all servers had the same patch level, the NFS export seemed properly configured, we were stumped.  Looking on the Nexus 7k, we saw that one of the ports in the VNX portchannel had a low Rx Power -11.30 dBm, and 75414 CRC errors on RX.  Once we replaced the SFP & Fiber Optic Cable, everything is happy again.