If your environment uses vSphere Virtual Machine Encryption, and if an error occurs on the ESXi host, the resulting core dump is encrypted to protect customer data. Core dumps that are included in the vm-support package are also encrypted.

Note: Core dumps can contain sensitive information. Follow your organization's data security and privacy policy when handling core dumps.

Core Dumps on ESXi Hosts

When an ESXi host, a user world, or a virtual machine fails, a core dump is generated, and the host reboots. If the ESXi host has encryption mode enabled, the core dump is encrypted using a key that is in the ESXi key cache. This key comes from the KMS. See How vSphere Virtual Machine Encryption Protects Your Environment for background information.

When an ESXi host is cryptographically "safe," and a core dump is generated, an event is created. The event indicates that a core dump occurred along with the following information: world name, occurring times, keyID of the key used to encrypt the core dump, and core dump filename. You can view the event in the Events viewer under Tasks and Events for the vCenter Server.

The following table shows encryption keys used for each core dump type, by vSphere release.

Table 1. Core Dump Encryption Keys
Core Dump Type Encryption Key (ESXi 6.5) Encryption Key (ESXi 6.7 and Later)
ESXi Kernel Host Key Host Key
User World (hostd) Host Key Host Key
Encrypted Virtual Machine (VM) Host Key Virtual Machine Key
What you can do after an ESXi host reboot depends on several factors.
  • In most cases, vCenter Server retrieves the key for the host from the KMS and attempts to push the key to the ESXi host after reboot. If the operation is successful, you can generate the vm-support package and you can decrypt or re-encrypt the core dump. See Decrypt or Re-Encrypt an Encrypted Core Dump.
  • If vCenter Server cannot connect to the ESXi host, you might be able to retrieve the key from the KMS. See Resolve Missing Key Issues.
  • If the host used a custom key, and that key differs from the key that vCenter Server pushes to the host, you cannot manipulate the core dump. Avoid using custom keys.

Core Dumps and vm-support Packages

When you contact VMware Technical Support because of a serious error, your support representative usually asks you to generate a vm-support package. The package includes log files and other information, including core dumps. If your support representatives cannot resolve the issues by looking at log files and other information, they might ask you to decrypt the core dumps and make relevant information available. To protect sensitive information such as keys, follow your organization's security and privacy policy. See Collect a vm-support Package for an ESXi Host That Uses Encryption.

Core Dumps on vCenter Server Systems

A core dump on a vCenter Server system is not encrypted. vCenter Server already contains potentially sensitive information. At the minimum, ensure that the vCenter Server is protected. See Securing vCenter Server Systems. You might also consider turning off core dumps for the vCenter Server system. Other information in log files can help determine the problem.