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Configuring a diagnostic coredump partition on an ESXi 5.x/6.x host (2004299)

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Purpose

This article provides steps to add a VMKcore diagnostic partition on a local or shared disk post-installation using the esxcli command line utility. A diagnostic partition can also be created using the vSphere Client. For more information, see:

The diagnostic coredump partition is used to capture the output of a purple diagnostic screen in the event of an ESXi host failure. For more information, see Configuring an ESX/ESXi host to capture a VMkernel coredump from a purple diagnostic screen (1000328).

Resolution

Listing currently configured diagnostic coredump partition on disk

To display the currently configured diagnostic coredump partition:

  1. Open a console session to the ESXi host, or the location where vSphere Command-Line Interface (vCLI) is installed.
  2. Retrieve the currently active diagnostic partition by running esxcli command line utility:

    esxcli system coredump partition get

    You see output similar to:

    Active: mpx.vmhba2:C0:T0:L0:7
    Configured: mpx.vmhba2:C0:T0:L0:7

Creating and activating a diagnostic coredump partition on disk

 
Note: Configuring a remote device using the ESXi host software iSCSI initiator is not supported.
 

To create a new diagnostic coredump partition on disk:

  1. Open a console session to the ESXi host. For more information, see the Log In to the ESXi Shell section in the vSphere Security guide.

    Note: Diagnostic partitions cannot be created using the vCLI, but existing diagnostic partitions can be activated.

  2. Select a storage device with at least 100 MB of free space that is accessible by the ESXi host. For more information, see Identifying disks when working with VMware ESX/ESXi (1014953).

    Note:
  3. Run the partedUtil command line utility to create a new partition, 100 MB in size, with type 0xFC = 252. Ensure that other existing partitions on the same disk are not affected. For more information, see Using the partedUtil command line utility on ESXi and ESX (1036609).

    Note:  Some environments may require a larger size.  If needed you will be prompted with the recommended size.

  4. Run the esxcli command line utility to list all accessible diagnostic partitions. Validate that the list of partitions includes the one created in step 3.

    esxcli system coredump partition list

    You see output similar to:

    Name                   Path                Active  Configured
    ---------------------  ------------------  ------  ----------
    mpx.vmhba2:C0:T0:L0:7  /vmfs/devices/....   false       false


  5. Set and activate one of the accessible diagnostic partitions using the esxcli command line utility. Either specify a device explicitly, or use the Smart Activate feature to automatically select one of the accessible diagnostic partitions:

    • To configure and activate a specific device partition by its VMkernel device path, run these commands:

      esxcli system coredump partition set --partition="Partition_Name"
      esxcli system coredump partition set --enable true


      For example:

      esxcli system coredump partition set --partition="mpx.vmhba2:C0:T0:L0:7"
      esxcli system coredump partition set --enable true


    • To automatically select and activate an accessible diagnostic partition, run this command:

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

  6. Validate that the diagnostic partition is now active by running this command:

    esxcli system coredump partition list

    You see output similar to:

    Name                   Path                Active  Configured
    ---------------------  ------------------  ------  ----------
    mpx.vmhba2:C0:T0:L0:7  /vmfs/devices/....    true        true

Activating or deactivating an existing diagnostic coredump partition on disk using Host Profiles

If a diagnostic partition is available on shared or local disks, it can be activated or deactivated across a group of ESXi 5.x/6.x hosts using Host Profiles. For more information, see the vSphere Host Profiles Guide.

To configure use of diagnostic coredump partitions using Host Profiles:
  1. Connect to vCenter Server using the vSphere Client.
  2. Click Home and select Host Profiles.
  3. Create or edit a host profile.
  4. Select Coredump Partition Settings > Fixed Coredump Partition Policy.
  5. The configuration option Enable or disable coredump partition is available. Specify the preferred option:

    • When deselected, the ESXi host deactivates any previously active diagnostic partition.
    • When selected, the ESXi host automatically selects and activates an accessible diagnostic partition. If a diagnostic partition is already configured, it is activated.

  6. Save and apply the host profile.

Additional Information

To extract contents from the VMKcore diagnostic partition after a purple screen error, see Collecting diagnostic information from an ESX or ESXi host that experiences a purple diagnostic screen (1004128).

See Also

Update History

04/23/2014 - Modified step 5 example for command esxcli system coredump partition set --enable true esxcli system coredump partition set --enable true --smart 02/11/2016 - Added ESXi 6.0 to Products. 05/18/2016 - Updated TSE note in Confidential section

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