In this example, there is a Network issue indicated by the red exclamation point in the Configure hosts box.
Investigate the network issue as follows:
- Click the link next to the red exclamation point, Network in this example.
- The link opens the Skyline Health window for the cluster, as shown.
- Click the vSAN: MTU check (ping with large packet size) link next to the red exclamation point. The vSAN MTU check window opens.Note: For more information about an issue, click the Info tab as shown in the previous figure, to access the ASK VMWARE link.
As shown in the figure above, jumbo frames are failing between the witness host and the vSAN cluster nodes. Jumbo frames must be enabled for vSAN cluster health checks to pass which requires the MTU to be set to at least 9000 bytes end-to-end.
From the witness host to each vSAN cluster host, jumbo frames must be configured in all places shown in the following table.
Table 11. Jumbo frame configuration points Item Jumbo frame configuration status Witness host vSAN VM kernel adapter Completed in the Configure jumbo frames and vSAN network on the witness host section of this guide. Witness host vSwitch Completed in the Configure jumbo frames and vSAN network on the witness host section of this guide. DCI Switch ports Completed in the Configure DCI switches section of this guide. Leaf Switch ports Completed when switches were placed in SFS mode. All ports are set to MTU 9216 by default. Stretched cluster host vSAN and vMotion VMkernel adapters Not done Stretched cluster vDS Not done - To set the MTU on the vSAN cluster host vSAN and vMotion VM kernel adapters, select a host in the stretched cluster the Inventory pane.
- In the right pane, select Configure > Networking > VMkernel adapters.
- Click the three dots next to the vSAN vmk adapter and click Edit. Set the MTU to 9000.
- Click OK.
- Click the three dots next to the vMotion vmk adapter and click Edit. Set the MTU to 9000 and click OK.
- Repeat the steps above for the remaining hosts in the stretched cluster.
- To set the MTU on the stretched cluster vDS, go to the top of the Inventory pane and click the networking icon .
- Right-click the vDS, named DSwitch in this example, and click Settings > Edit Settings.
- In the Edit Settings window, click the Advanced tab.
- Change MTU (Bytes) to 9000, as shown.
- Click OK.
- After making the MTU settings above, select the stretched cluster in the Inventory pane and select Configure > Configuration > Quickstart.
- Check the status of the validation tests in the Configure hosts box. All tests pass in this example, as shown. Note: If there are any warnings or errors still reported in the Configure Hosts box, click the link provided for more information to resolve the remaining issues.