A virtual machine running on an ESX/ESXi host can encounter issues that prevent it from being able to function and become unresponsive. This may stem from issues not with the virtual machine itself, but from a configuration issue on the ESX/ESXi host. This article describes some common ESX/ESXi host configuration issues which can cause a virtual machine to become unresponsive.

For more general troubleshooting of unresponsive virtual machines on ESX/ESXi, see Troubleshooting a virtual machine that has stopped responding (1007819).

• Ensure the hardware belonging to the ESX host is fully operational. There may be hardware issues that have interfered with the operation of the ESX host machine. These errors may cause a failure in the host that result in a purple diagnostics screen displaying memory information. These purple diagnostic screens are a result of either the VMkernel or the service console failing. For hardware issues that have caused purple screen errors, review Collecting diagnostic information from an ESX or ESXi host that experiences a purple diagnostic screen (1004128) and contact VMware Technical Support to open a Support Request.
  
  
• Determine if you experiencing intermittent or unpredictable errors. Even if you have not encountered any purple screen issues, you may still be encountering hardware issues. Faulty hardware does not necessarily result in a failure by the service console or VMkernel. Hardware issues can also cause intermittent and unpredictable failures. To rule out the hardware as a possible cause, see Verifying your hardware is functioning correctly (1003690)
  
  
• In a NUMA hardware platform, physical memory should be allocated to each NUMA node in a balanced manner. Imbalance between NUMA nodes may result in performance impact or stability issues. For more information, see ESX host console message: Significant imbalance between NUMA nodes detected (1018754).
  
  
• Storage may be inaccessible through part or all of a cluster. Without access to backing storage, virtual machines stop functioning. To determine the location of the virtual machine's hard disk and whether the storage is accessible, see Verifying that ESX/ESXi virtual machine storage is accessible (1003751) and ESX server virtual machines stop responding due to shared storage connectivity issues (1004144).
  
  
• Storage space on datastores may be constraint, such that there is insufficient disk space available for virtual machines. Insufficient space can result in virtual machines blocking until space becomes available. To determine how much disk space a virtual machine requires and how much is available, see Verifying sufficient free disk space for an ESX/ESXi virtual machine (1003755) and Investigating disk space on an ESX/ESXi host (1003564).
  
  
• Resource pools may have been created which aggressively limit resource usage of virtual machines, such that virtual machines are starved for those resources and cannot perform meaningful work. For more information, see Impact of virtual machine memory and CPU resource limits (1033115) and the Resource Management Guide for your version of ESX/ESXi Server or VirtualCenter/vCenter Server.

For related troubleshooting information, see Troubleshooting a virtual machine that has stopped responding (1007819).