NDCTL User Guide


ndctl is a utility for managing the Linux LIBNVDIMM Kernel subsystem. It is designed to work with various non-volatile memory devices (NVDIMMs) from different vendors. The LIBNVDIMM subsystem defines a kernel device model and control message interface for platform NVDIMM resources like those defined by the ACPI v6.0 NFIT (NVDIMM Firmware Interface Table). The latest ACPI and UEFI specifications can be found at uefi.org. Operations supported by ndctl include:

  • Provisioning capacity (namespaces)

  • Enumerating Devices

  • Enabling and Disabling NVDIMMs, Regions, and Namespaces

  • Managing NVDIMM Labels

Installing NDCTL

See Installing NDCTL in the Getting Started Guide.

Basic Usage

The ndctl command is designed to be user friendly. Once installed, a list of commands can be shown using any of the following:

1) With no arguments or options, ndctl shows a simple usage message:

# ndctl
usage: ndctl [--version] [--help] COMMAND [ARGS]
See 'ndctl help COMMAND' for more information on a specific command.
ndctl --list-cmds to see all available commands

2) Using ndctl help displays basic help and syntax:

# ndctl help
usage: ndctl [--version] [--help] COMMAND [ARGS]
See 'ndctl help COMMAND' for more information on a specific command.
ndctl --list-cmds to see all available commands

Below is an example of using the ndctl help command to launch the create-namespace man page:

# ndctl help create-namespace

3) Using ndctl --list-cmds lists all commands as a single list.

# ndctl --list-cmds

An alternative method for listing commands uses the TAB key completion feature of ndctl. By executing ndctl <TAB> <TAB> we can list the commands, eg:

# ndctl <TAB> <TAB>
check-labels disable-namespace help monitor update-firmware zero-labels
check-namespace disable-region init-labels read-labels update-passphrase
clear-errors enable-dimm inject-error remove-passphrase version
create-namespace enable-namespace inject-smart sanitize-dimm wait-overwrite
destroy-namespace enable-region list setup-passphrase wait-scrub
disable-dimm freeze-security load-keys start-scrub write-labels

TAB Command and Argument Completion

ndctl supports command completion using the TAB key. For example, typing ndctl enable-<TAB> lists all commands beginning with 'enable', eg:

# ndctl enable-<TAB>
enable-dimm enable-namespace enable-region

TAB completion also works with command arguments. For example, typing ndctl enable-dimm <TAB> will show all available command arguments. For example, the 'enable-dimm' command can enable one, more than one, or all NVDIMMs. It will list all available NVDIMMs (nmem) devices when using the TAB completion, eg:

# ndctl enable-dimm <TAB>
all nmem0

Getting Help

NDCTL ships with a man page for each command. Each man page describes the required arguments and features in detail. Man pages can be found and accessed using the man or ndctl utilities. The following man -k ndctl searches for any man page containing the "ndctl" keyword:

# man -k ndctl
ndctl (1) - Manage "libnvdimm" subsystem devices (Non-volatile Memory)
ndctl-check-labels (1) - determine if the given dimms have a valid namespace index block
ndctl-check-namespace (1) - check namespace metadata consistency
ndctl-clear-errors (1) - clear all errors (badblocks) on the given namespace
ndctl-create-namespace (1) - provision or reconfigure a namespace
ndctl-destroy-namespace (1) - destroy the given namespace(s)
ndctl-disable-dimm (1) - disable one or more idle dimms
ndctl-disable-namespace (1) - disable the given namespace(s)
ndctl-disable-region (1) - disable the given region(s) and all descendant namespaces
ndctl-enable-dimm (1) - enable one more dimms
ndctl-enable-namespace (1) - enable the given namespace(s)
ndctl-enable-region (1) - enable the given region(s) and all descendant namespaces
ndctl-freeze-security (1) - Set the given DIMM(s) to reject future security operations
ndctl-init-labels (1) - initialize the label data area on a dimm or set of dimms
ndctl-inject-error (1) - inject media errors at a namespace offset
ndctl-inject-smart (1) - perform smart threshold/injection operations on a DIMM
ndctl-list (1) - dump the platform nvdimm device topology and attributes in json
ndctl-load-keys (1) - load the kek and encrypted passphrases into the keyring
ndctl-monitor (1) - Monitor the smart events of nvdimm objects
ndctl-read-labels (1) - read out the label area on a dimm or set of dimms
ndctl-remove-passphrase (1) - Stop a DIMM from locking at power-loss and requiring a passphrase to access media
ndctl-sanitize-dimm (1) - Perform a cryptographic destruction or overwrite of the contents of the given NVDIMM(s)
ndctl-setup-passphrase (1) - setup and enable the security passphrase for an NVDIMM
ndctl-start-scrub (1) - start an Address Range Scrub (ARS) operation
ndctl-update-firmware (1) - provides for updating the firmware on an NVDIMM
ndctl-update-passphrase (1) - update the security passphrase for an NVDIMM
ndctl-wait-overwrite (1) - wait for an overwrite operation to complete
ndctl-wait-scrub (1) - wait for an Address Range Scrub (ARS) operation to complete
ndctl-write-labels (1) - write data to the label area on a dimm
ndctl-zero-labels (1) - zero out the label area on a dimm or set of dimms

Note: If man -k ndctl returns "ndctl: nothing appropriate." or similar, see the Troubleshooting section to manually build the indexes.

Additionally, executing ndctl help <command> can be used to display the man page for the command, eg:

# ndctl help enable-dimm

A list of ndctl man pages are available online. See 'NDCTL Man Pages' for a complete list.

Displaying Bus, NVDIMM, Region, and Namespace Information

The ndctl list command is a very powerful and feature rich command. A list of options is shown below:

# ndctl list -?
Error: unknown switch `?'
usage: ndctl list [<options>]
-b, --bus <bus-id> filter by bus
-r, --region <region-id>
filter by region
-d, --dimm <dimm-id> filter by dimm
-n, --namespace <namespace-id>
filter by namespace id
-m, --mode <namespace-mode>
filter by namespace mode
-t, --type <region-type>
filter by region-type
-U, --numa-node <numa node>
filter by numa node
-B, --buses include bus info
-D, --dimms include dimm info
-F, --firmware include firmware info
-H, --health include dimm health
-R, --regions include region info
-N, --namespaces include namespace info (default)
-X, --device-dax include device-dax info
-i, --idle include idle devices
-M, --media-errors include media errors
-u, --human use human friendly number formats

Using the filters is a powerful way to limit the output.


To list all active/enabled namespaces:

# ndctl list -N

To list all active/enabled regions:

# ndctl list -R

To list all active/enabled NVDIMMs:

# ndctl list -D

To list all active/enabled NVDIMMs, Regions, and Namespaces:

# ndctl list -DRN

To list all active/enabled and disabled/inactive (idle) NVDIMMs, Regions, and Namespaces:

# ndctl list -DRNi

To list all active/enabled and disabled/inactive (idle) NVDIMMs, Regions, and Namespaces with human readable values:

# ndctl list -iNuRD