When you see the VMware host’s message is not responding, some of us will start panicking because you might think that there is no problem-solving solution for this particular issue.
The leading causes of the VMware host not responding issue
There are many reasons why ESXi disappears in the vCenter server view. It is not always pleasant to find out that one of your ESXi hosts is not online. If this host is part of the High Availability (HA) cluster and the virtual machines (VMs) were working, those VMs successfully restarted on the remaining hosts while you slept.
Moreover, there may be a situation where this host is just a standalone host, and you need to find out quickly what is going on. In any case, the host will look gray. Here are the symptoms:
- The ESXi host is disabled (gray) and is displayed as Unresponsive
- The ESXi host is disabled (gray) and is shown as Off
- If the vCenter server does not receive a heartbeat from the ESXi host, it goes into an unresponsive state:
- The backup and layout of the virtual machine can create complex tasks related to the I / O load, which will lead to unresponsive problems.
- The virtual machine may not respond when the hard disk runs out of space.
- The virtual machine’s operating system may cause the VM to appear unresponsive.
- Virtual machine disk controllers are not set up according to best practices.
- Your network contains a firewall between the ESXi / ESX host and the vSphere client.
Verify that the ESXi host is enabled by checking logs
One of the prime things to check is probably the host itself and to check if the power has not been turned off or if the power supply has reached the end of the battery, after which the host has turned off. If your ESXi host is configured in a way to redirect logs to another server, you can check those logs and possibly find out why the host has restarted.
Log files in the vCenter server agent can help you select gather performance data collected from the vCenter server diagnostic data system logs. ESXi log files located in the vSphere web client along with ESXi management agents resolves the issue with the VMware ESXi hosts.
ESXi does not save logs by restarting, so you will not check them if the logs are not redirected. You will need to check this log file: hostd.log. And it would be best if you were looking for something similar to “reboot” or “HostSystem.reboot”. You can check the advanced ESXi configuration by selecting the host, going to Configuration> Advanced System Settings, and entering Syslog in the search box.
Solving the issue
VMware Virtual Machine that does not respond to connection attempts and may not be able to respond to any power attempts.
There are various reasons why a virtual machine may end up in a non-responsive state. This article on VMware-ESXi.com allows you to identify and resolve these common causes and, once determined, restore the virtual machine to working condition.
The information available on many issues may prove unconvincing. Hanging servers’ purple screens without disc ejection or disk defects can leave the server with little recorded information about a situation.
Although the root cause of this interruption may not be achievable, you have to be better prepared for this particular problem next time.
Faulty processors can manifest as unusual behavior, such as abrupt reboots hanging or purple screens. The CPU often generates an exception captured by VMkernel and handled with a purple screen.
Fix 1: Reconnect a disconnected host
Verify that reconnecting the ESXi host or reconnecting the ESXi host resolves the issue. Just right-click the host and select Connection > Connect to reconnect the host.
VMware recommends we diagnose communication issues between ESXi and vCenter Server. Or better to say, when you have doubts about the connection with your host, disconnect, wait until the tasks are entirely, and then reconnect the host back to the vCenter Server.
Fix 2: Verify port 902
The second fix we are going to show is that you can verify your connection from the vCenter Server system to the ESXi host on TCP/UDP port 902. The server utilizes this port for host access in order to other hosts for migration and provisioning, ESXi authentication traffic, and remote console traffic (xinetd/vmware-authd).
Also, use Telnet for vSphere Client access to VM consoles or a (UDP) status update (heartbeat) connection from ESXi to vCenter Server. In the command prompt window (cmd), type the following:
telnet server port
A server is a hostname or IP address of the server, and a port is the port you want to connect to.
Fix 3: Check connectivity via FQDN and IP address
You should also check if you have a network connection from the vCenter server to the ESXi host with an IP and a fully qualified domain name (FQDN).
To do this, connect to the box on your vCenter Windows server and open a command prompt where you can check if you can ping your ESXi host via IP address and FQDN. Using a Photon OS Linux vCenter Server Appliance (VCSA), you can open a Linux command shell terminal and execute a ping command via the IP address and FQDN.
If you do not see a response, you can look at your DNS server to see any DNS resolution issues.
Fix 4: Check underlying storage issues
Due to fundamental storage issues, ESXi hosts can be disconnected from the vCenter server issues.
Sharing can be a problem, and in this case, you may experience multiple hosts in offline status. It could also be a failed network interface card (NIC), which, due to a problem, does not maintain a connection to the vCenter Server system. You may experience some of these symptoms:
- Storage connection problems;
- The initiators of the ESXi host are not announced in the sequence;
- The ESXi host could not mount the sharing;
- Storage problems can be multiple because you may be using different storage protocols such as iSCSI, NFS, or SAN.
Troubleshooting ESXi connectivity can be complex or not at all. Simply, we must be consistent and examine additional ways until we crack the problem. The most alarming issues are always when you have intermittent disconnections.
In such cases, it’s more complicated than average. For such problems, VMware-ESXi suggests configuring ESXi logs to a remote host and using a dedicated Syslog server or alternative, such as VMware Log Insight.
It has machine learning and searching capabilities to find problems occurring during certain periods or certain workloads on specific days of the month. VMware host not responding state is one of the most common issues on the VMware ESXi host.