If the size of your available core dump partition is insufficient, you can configure ESXi to use a file for diagnostic information.

Typically, a core dump partition of 2.5 GB is created during ESXi installation. For upgrades from ESXi 5.0 and earlier, the core dump partition is limited to 100 MB. For this type of upgrade, during the boot process the system might create a core dump file on a VMFS datastore. If it does not create a core dump file, you can manually create the file.
Note: Software iSCSI and software FCoE are not supported for core dump file locations.

Prerequisites

Install vCLI or deploy the vSphere Management Assistant (vMA) virtual machine. See Getting Started with vSphere Command-Line Interfaces. For troubleshooting, run esxcli commands in the ESXi Shell.

Procedure

  1. Create a VMFS datastore core dump file by running the following command:
    esxcli system coredump file add

    The command takes the following options, but they are not required and can be omitted:

    Option Description
    --datastore | -d datastore_UUID or datastore_name If not provided, the system selects a datastore of sufficient size.
    --file | -f file_name If not provided, the system specifies a unique name for the core dump file.
    --size |-s file_size_MB If not provided, the system creates a file of the size appropriate for the memory installed in the host.
  2. Verify that the file has been created:
    esxcli system coredump file list
    You can see the output similar to the following: 
    Path                                             Active Configured Size
------------------------------------------------ ------ ---------- ---------
/vmfs/volumes/52b021c3-.../vmkdump/test.dumpfile false  false      104857600
  3. Activate the core dump file for the host:
    esxcli system coredump file set

    The command takes the following options:

    Option Description
    --path | -p The path of the core dump file to use. The file must be pre-allocated.
    --smart | -s This flag can be used only with --enable | -e=true. It causes the file to be selected using the smart selection algorithm.

    For example,

    esxcli system coredump file set --smart --enable true

  4. Verify that the core dump file is active and configured:
    esxcli system coredump file list
    The output similar to the following indicates that the core dump file is active and configured: 
    Path                                             Active Configured Size
------------------------------------------------ ------ ---------- ---------
/vmfs/volumes/52b021c3-.../vmkdump/test.dumpfile True   True       104857600

What to do next

For information about other commands you can use to manage the core dump files, see the vSphere Command-Line Interface Reference documentation.