Man1 - ndctl-init-labels.1

ndctl-init-labels - initialize the label data area on a dimm or set of dimms

  ndctl init-labels <nmem0> [<nmem1>..<nmemN>] [<options>]

The namespace label area is a small persistent partition of capacity available on some NVDIMM devices. The label area is used to resolve aliasing between pmem and blk capacity by delineating namespace boundaries. By default, and in kernels prior to v4.10, the kernel only honors labels when a DIMM aliases PMEM and BLK capacity. Starting with v4.10 the kernel will honor labels for sub-dividing PMEM if all the DIMMs in an interleave set / region have a valid namespace index block.

This command can be used to initialize the namespace index block if it is missing or reinitialize it if it is damaged. Note that reinitialization effectively destroys all existing namespace labels on the DIMM.

Find the DIMMs that comprise a given region:

    # ndctl list -RD --region=region1
    {
      "dimms":[
        {
          "dev":"nmem0",
          "id":"8680-56341200"
        }
      ],
      "regions":[
        {
          "dev":"region1",
          "size":268435456,
          "available_size":0,
          "type":"pmem",
          "mappings":[
            {
              "dimm":"nmem0",
              "offset":13958643712,
              "length":268435456
            }
          ]
        }
      ]
    }

Disable that region so the DIMM label area can be written from userspace:

    # ndctl disable-region region1

Initialize labels:

    # ndctl init-labels nmem0

Re-enable the region:

    # ndctl enable-region region1

Create a namespace in that region:

    # ndctl create-namespace --region=region1

<memory device(s)>

A nmemX device name, or a dimm id number. Restrict the operation to the specified dimm(s). The keyword all can be specified to indicate the lack of any restriction, however this is the same as not supplying a –dimm option at all.

-s, –size=

Limit the operation to the given number of bytes. A size of 0 indicates to operate over the entire label capacity.

-O, –offset=

Begin the operation at the given offset into the label area.

-b, –bus=

A bus id number, or a provider string (e.g. “ACPI.NFIT”). Restrict the operation to the specified bus(es). The keyword all can be specified to indicate the lack of any restriction, however this is the same as not supplying a –bus option at all.

-v

Turn on verbose debug messages in the library (if ndctl was built with logging and debug enabled).

-f, –force

Force initialization of the label space even if there appears to be an existing / valid namespace index. Warning, this will destroy all defined namespaces on the dimm.

-V, –label-version

Initialize with a specific version of labels from the namespace label specification. Defaults to 1.1

Copyright © 2016 - 2020, Intel Corporation. License GPLv2: GNU GPL version 2 http://gnu.org/licenses/gpl.html. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.

ndctl-create-namespace(1), UEFI NVDIMM Label Protocol http://www.uefi.org/sites/default/files/resources/UEFI_Spec_2_7.pdf