ndctl-init-labels man page

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

Synopsis

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

Description

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.

Example

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

Options

<memory device(s)>...

One or more nmemX device names. The keyword all can be specified to operate on every dimm in the system, optionally filtered by bus id (see --bus= option).

-b, --bus=

Limit operation to memory devices (dimms) that are on the given bus. Where bus can be a provider name or a bus id number.

-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.

See Also

ndctl-create-namespace(1), UEFI NVDIMM Label Protocol[1]

Notes

1.

UEFI NVDIMM Label Protocol
http://www.uefi.org/sites/default/files/resources/UEFI_Spec_2_7.pdf

Referenced By

ndctl-create-namespace(1).

03/27/2018 ndctl 59.3 ndctl Manual