---
name: "ndctl-read-infoblock"
section: "1"
platform: "linux"
package: "ndctl"
version: "85-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/ndctl-read-infoblock"
---

# ndctl-read-infoblock(1)

read and optionally parse the info-block a namespace

## NAME

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

## SYNOPSIS

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

## DESCRIPTION

As described in the theory of operation section of [ndctl-create-namespace(1)](/ndctl-create-namespace/1.md), 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

```
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

\<namespace(s)\>

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 © 2016 - 2022, 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.

## SEE ALSO

[ndctl-create-namespace(1)](/ndctl-create-namespace/1.md), *UEFI NVDIMM Label Protocol* \<http://www.uefi.org/sites/default/files/resources/UEFI\_Spec\_2\_7.pdf\>