ESXi 5.x - "Performance has deteriorated. I/O latency increased" messages in the vmkernel logs.

Steps to identify\troubleshoot the issue

• Verify if the iSCSI environment is accordance with Equallogic's network configuration requirements and recommendation for high performance and reliability.

• Verify if the Hosts NICs, Switches and Arrays are at latest drivers\firmware revision.

• Verify if the ESX hosts have Delayed ACK disabled, and the iSCSI login timeout settings are set to 60 seconds:

  • Telnet\SSH directly to the host IP address and run the following commands and check the results:
    vmkiscsid --dump-db | grep Delayed
    vmkiscsid --dump-db | grep login_timeout
    These values should reflect "0" and "60" respectively.

  • Disable Delayed ACK and change the iSCSI login timeout settings if needed

   

• In case further troubleshooting is needed, please contact Dell Tech support. The Following logs will be helpful:

  • VMsupport logs from the ESX hosts.

  • Switches Logs

  • SANHQ Archive if available:

    • Start SANHQ and select Monitor

    • On the drop down select create archive.

    • Choose ‘select all groups’ or select a specific group.

    • Once selected, click on ‘create archive’ The file is in *.gprx format

     

   

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Not Applicable