Server with Emulex 10Gb CNA intermittently sees 100% utilization over SAN with no operations completing

Solution Verified - Updated -


A Red Hat Enterprise Linux application server is having some issues with I/O utilization on some LUN paths. The system has 4 paths to each LUN, but when the problem occurs we've been able to see via iostats where one of the 4 paths for a LUN goes to 100% utilization while the other paths are at 0%.

Analysis from the SAN vendor indicates that they are saturating the links to the storage, however after congestion, the storage array is sending an XFER_READY command to which the server is not responding.


  • Red Hat Enterprise Linux
  • Emulex Corporation OneConnect 10Gb CNA, firmware 4.1.450.1707

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