Microsoft Windows warning event ID:49 Receive-Side Scaling (RSS) is limited to four queues - IBM Flex Systems

Resolving The Problem

Source

RETAIN tip: H212891

Symptom

After starting, the Microsoft Windows Event log contains a system warning event ID:49 as follows:

This warning could also occur for system board Lan-On-Motherboard (LOM) as well as multi-port expansion Network Interface Controller (NIC) Emulex adapters.

Affected configurations

The system can be any of the following IBM servers:

• Flex System x240 Compute Node, type 7863, any model
• Flex System x240 Compute Node, type 7863 E5-xxxxV2, any model
• Flex System x240 Compute Node, type 8737, any model
• Flex System x240 Compute Node, type 8737 E5-xxxxV2, any model
• Flex System x240 Compute Node, type 8738, any model
• Flex System x440 Compute Node, type 2584, any model
• Flex System x440 Compute Node, type 7917, any model

The system is configured with at least one of the following:

• Microsoft Windows Server 2008, Enterprise 64-bit, any service pack
• Microsoft Windows Server 2012, any service pack

The system is configured with one or more of the following IBM options:

• Flex System EN4054 Quad-Port 10 Gb Ethernet Adapter, option part number 81Y3124, any replacement part number
  

Note: This does not imply that the network operating system will work under all combinations of hardware and software.

Please see the compatibility page for more information:

Workaround

The Emulex adapter (LOM or expansion card) is functioning normally. The default value for the number of Receive-Side Scaling (RSS) queues currently in use is listed in the message.

Unified Extensible Firmware Interface (UEFI) or Advanced Settings Utility (ASU) configuration can be used to enable Advanced mode within the Emulex LOM or Expansion card firmware.

Note: Prior to enabling Advanced mode and altering the default RSS queue values, the operating system documentation, driver and knowledge base articles should be reviewed, because increasing the number of RSS queues can have an impact on processor utilization and potential conflict with operating system specific network load balancing.

The example below uses an EN4054 Quad-Port Adapter in pNIC mode:

To enable Advanced mode using the UEFI configuration interface, perform the following steps:

1. On node boot, use the F1 key to enter configuration.
2. Select System Settings.
3. Select Network.
4. The Network Device List is displayed. Depending on the type and mode of the NIC (for example: pNIC, vNIC or UFP), the Network Device List contains differing numbers of devices listed.

   (where pNIC = Protocol NIC, vNIC = virtual NIC, UFP = Unified Fabric Port)

5. When users select an entry in the Network Device List, verify that the resulting screen displays the NIC Manufacturer and speed, as in the following example:

   Emulex 10G NIC: Bus:Dev:

6. .Select the first MAC:xx in the Network Device List.
7. For Quad-Port or multi-LOM configurations, users need to repeat for the first MAC:xx in each pair. The second MAC:xx in each pair automatically set.
   

   MAC:00:90:FA:27:47:BC Slot 1 PFA 17:0:0 <--Select first MAC:00:90:FA:27:47:BE Slot 1 PFA 17:0:1 MAC:00:90:FA:27:47:B8 Slot 1 PFA 27:0:0 <--Select second MAC:00:90:FA:27:47:BA Slot 1 PFA 27:0:15)

8. On the Media Access Control (MAC) page, select the Emulex 10G NIC entry at the top of the screen.
9. Select Advanced Mode and then Enable in the pop-up menu.
10. Return to the Network page.
11. If there are more than two devices in the Network Device List, repeat for the first of each pair ( <-- Select as above, in Step 7).
12. Return to the System Configuration and Boot Management page and click Save Settings.

Additional information

This warning message is an informational alert and indicates that the RSS function within the Emulex NIC ASIC firmware is using the default number of RSS queues.

RSS provides the capability to queue incoming network packet traffic to more than one processor, thus distributing the load.

By default, the RSS function is enabled, but using a set number of queues.

Enabling Advanced Mode allows configuration of additional RSS queues. The maximum number of queues is dependent on the CPU configuration present on the specific node in use. Changing the values for the RSS queue count is accomplished through the NIC driver.

As noted above, caution should be used when increasing the number of RSS queues above the default. The Emulex driver information should be consulted along with operating system specific knowledge base documentation.

The following URL provides an example of the information available on RSS functions.

http://emulex.force.com/knowledgebase/articles/How_To/RSS-and-VMQ-Tuning-on-Windows-Server/?l=en_US&fs=Search&pn=1

Note: This Knowledge Base article lists the maximum RSS queue count as 8. The hardware implementation in this RETAIN Tip supports 16 queues.