NDCTL-READ-INFOBLOCK(1) ndctl Manual NDCTL-READ-INFOBLOCK(1)

# [NAME](#NAME)

ndctl-read-infoblock - read and optionally parse the info-block a namespace

# [SYNOPSIS](#SYNOPSIS)

```
ndctl read-infoblock <namespace0.0> [<namespace1.0>..<namespaceN.Y>] [<options>]
```

# [DESCRIPTION](#DESCRIPTION)

As described in the theory of operation section of [ndctl-create-namespace(1)](/man/os/ndctl/ndctl-create-namespace.1), the raw capacity of a namespace may encapsulate a personality, or mode of operation. Specifically, the mode may be set to one of "sector", "fsdax", and "devdax". Each of those modes is defined by an info-block format that uniquely identifies the mode of operation. The read-infoblock command knows the location (relative to the start of the namespace) and field definition of those data structures.

Note that unlike a partition table info-block is not exposed by default, so the namespace needs to be disabled before the info-block can be accessed.

# [EXAMPLE](#EXAMPLE)

```
ndctl disable-namespace namespace0.0
disabled 1 namespace
ndctl read-infoblock -j namespace0.0
[


  {


    "dev":"namespace0.0",


    "signature":"NVDIMM_PFN_INFO",


    "uuid":"56b11990-66b1-4d91-9cac-ca084c051259",


    "parent_uuid":"00000000-0000-0000-0000-000000000000",


    "flags":0,


    "version":"1.3",


    "dataoff":69206016,


    "npfns":1031680,


    "mode":2,


    "start_pad":0,


    "end_trunc":0,


    "align":2097152


  }
]
```

# [OPTIONS](#OPTIONS)

&lt;namespace(s)&gt;

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

-V, --verify

Attempt to validate that the info-block is self consistent by validating the embedded checksum, and that info-block formats that contain a *parent-uuid* attribute also match the base-uuid of the namespace.

-o, --output

Output file

-j, --json

Parse the info-block data into json.

-u, --human

Enable json output and convert number formats to human readable strings, for example show the size in terms of "KB", "MB", "GB", etc instead of a signed 64-bit numbers per the JSON interchange format (implies --json).

-r, --region=

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

# [COPYRIGHT](#COPYRIGHT)

Copyright © 2016 - 2022, Intel Corporation. License GPLv2: GNU GPL version 2 &lt;http://gnu.org/licenses/gpl.html&gt;. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.

# [SEE ALSO](#SEE_ALSO)

[ndctl-create-namespace(1)](/man/os/ndctl/ndctl-create-namespace.1), *UEFI NVDIMM Label Protocol* &lt;http://www.uefi.org/sites/default/files/resources/UEFI\_Spec\_2\_7.pdf&gt;

2026-08-31 ndctl

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Document: ndctl-read-infoblock(1) from ndctl 85-r2 (Chainguard OS)
Source: https://github.com/pmem/ndctl