NVME-WDC-CAP-DIAG(1) NVMe Manual NVME-WDC-CAP-DIAG(1)

# [NAME](#NAME)

nvme-wdc-cap-diag - Retrieve WDC device's diagnostic log and save to file.

# [SYNOPSIS](#SYNOPSIS)

```
nvme [<global-options>] wdc cap-diag <device>


                        [--output-file=<FILE>, -O <FILE>]


                        [--transfer-size=<SIZE>, -s <SIZE>]
```

# [DESCRIPTION](#DESCRIPTION)

For the NVMe device given, sends the WDC Vendor Unique Capture-Diagnostics request and saves the result to a file.

The &lt;device&gt; parameter is mandatory NVMe character device (ex: /dev/nvme0).

This will only work on WDC devices supporting this feature. Results for any other device are undefined.

# [OPTIONS](#OPTIONS)

-O &lt;FILE&gt;, --output-file=&lt;FILE&gt;

Output file; defaults to device serial number followed by "cap\_diag" suffix

-s &lt;SIZE&gt;, --transfer-size=&lt;SIZE&gt;

Transfer size; defaults to 0x10000 (65536 decimal) bytes

# [GLOBAL OPTIONS](#GLOBAL_OPTIONS)

The following options are defined at the top-level nvme command and are available to this subcommand:

--dry-run

Print the command that would be executed, but do not actually execute it.

--no-ioctl-probing

Disable probing for 64-bit IOCTL support.

--no-retries

Disable retry logic on transient errors.

-o &lt;fmt&gt;, --output-format=&lt;fmt&gt;

Set the reporting format to *normal*, *tabular, 'json*, or *binary*. Only one output format may be used at a time.

--output-format-version=&lt;version&gt;

Select the output format version. Version *1* uses the original field naming, while version *2* (default) provides more consistent and script-friendly field names.

--timeout=&lt;ms&gt;

Set the timeout for the command in milliseconds.

-v, --verbose

Increase the level of detail in the output. May be specified multiple times to further increase verbosity.

These options can also be set as machine-wide defaults in [nvme-cli.conf(5)](/man/os/nvme-cli/nvme-cli.conf.5). A command-line flag always overrides the file.

# [EXAMPLES](#EXAMPLES)

•Gets the capture diagnostics log from the device and saves to default file in current directory (e.g. STM00019F3F9cap\_diag.bin):

```
# nvme wdc cap-diag /dev/nvme0
```

•Gets the capture diagnostics log from the device and saves to defined file in current directory (e.g. testSTM00019F3F9cap\_diag.bin):

```
# nvme wdc cap-diag /dev/nvme0 -O test
```

•Gets the capture diagnostics log from the device and saves to defined file with pathname (e.g. /tmp/testSTM00019F3F9cap\_diag.bin):

```
# nvme wdc cap-diag /dev/nvme0 -O /tmp/test
```

•Gets the capture diagnostics log from the device transferring the data in 64k chunks and saves to default file in current directory (e.g. STM00019F3F9internal\_fw\_log.bin):

```
# nvme wdc cap-diag /dev/nvme0 -s 0x10000
```

•Gets the capture diagnostics log from the device transferring the data in 16k chunks and saves to default file in current directory (e.g. STM00019F3F9internal\_fw\_log.bin):

```
# nvme wdc cap-diag /dev/nvme0 -s 16384
```

# [NVME](#NVME)

Part of the nvme-user suite.

09/18/2026 NVMe

---

Document: nvme-wdc-cap-diag(1) from nvme-cli 3.1-r0 (Chainguard OS)
Source: https://github.com/linux-nvme/nvme-cli