VMware vCenter collects data from ESXi servers with an agent. When this agent crashes, no performance data is available from the host and any VM that runs on the host.
Usually this problem can be fixed by restarting the VMware Management Agent. VMware provides information on how to do this.
- Troubleshooting gaps in performance data or missing performance data in vCenter Server (1003878) (Step 1 is the mostly likely resolution.)
Step 1 gives the following link:
Note that this link is especially relevant when you are using HA (high availability) as it gives instructions to restart data collection agent without the HA taking any action. Specifically, see the instructions after "Caution: Ensure Automatic Startup/Shutdown of virtual machines is disabled before running this command or you risk rebooting the virtual machines."
To verify that the existence of this problem and to determine whether it has been solved, use the vCenter Client to observe whether performance data is available for VMs running on impacted hosts. To observe performance data, open vCenter Client and go: