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

Note: VMFS datastores on software iSCSI do not support core dump files.

Prerequisites

  • Make sure that the amount of available space in the datastore for a core dump file is twice as large as the recommended file size. For more information, see the Knowledge Base article 2058416.
  • Install ESXCLI. See Getting Started with ESXCLI. 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
    --auto | -a Automatically create a file if none found.
    --datastore | -d datastore_UUID or datastore_name Specify the datastore for the dump file. If not provided, the system selects a datastore of sufficient size.
    --enable | -e Enable the diagnostic file after creation.
    --file | -f file_name Specify the file name of the dump file. If not provided, the system creates a unique name for the file.
    --size |-s file_size_MB Set the size in MB of the dump file. 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
    --enable |-e Enable or disable the dump file. This option cannot be specified when unconfiguring the dump file.
    --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

    --unconfigure | -u Unconfigure the current VMFS dump file.
  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 ESXCLI Reference documentation.