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<body class="manpage">
<div id="header">
<h1>
nvme-discover(1) Manual Page
</h1>
<h2>NAME</h2>
<div class="sectionbody">
<p>nvme-discover -
Send Get Log Page request to Discovery Controller.
</p>
</div>
</div>
<div id="content">
<div class="sect1">
<h2 id="_synopsis">SYNOPSIS</h2>
<div class="sectionbody">
<div class="verseblock">
<pre class="content"><em>nvme discover</em> [--transport=<trtype> | -t <trtype>]
[--nqn=<subnqn> | -n <subnqn>]
[--traddr=<traddr> | -a <traddr>]
[--trsvcid=<trsvcid> | -s <trsvcid>]
[--host-traddr=<traddr> | -w <traddr>]
[--host-iface=<iface> | -f <iface>]
[--hostnqn=<hostnqn> | -q <hostnqn>]
[--hostid=<hostid> | -I <hostid>]
[--raw=<filename> | -r <filename>]
[--device=<device> | -d <device>]
[--config=<filename> | -J <filename>]
[--keep-alive-tmo=<sec> | -k <sec>]
[--reconnect-delay=<#> | -c <#>]
[--ctrl-loss-tmo=<#> | -l <#>]
[--nr-io-queues=<#> | -i <#>]
[--nr-write-queues=<#> | -W <#>]
[--nr-poll-queues=<#> | -P <#>]
[--queue-size=<#> | -Q <#>] [--keyring=<#>]
[--tls_key=<#>] [--hdr-digest | -g] [--data-digest | -G]
[--persistent | -p] [--quiet] [--tls] [--concat]
[--dump-config | -O] [--output-format=<fmt> | -o <fmt>]
[--force] [--nbft] [--no-nbft] [--nbft-path=<STR>]
[--context=<STR>]
[--output-format=<fmt> | -o <fmt>] [--verbose | -v]</pre>
<div class="attribution">
</div></div>
</div>
</div>
<div class="sect1">
<h2 id="_description">DESCRIPTION</h2>
<div class="sectionbody">
<div class="paragraph"><p>Send one or more Get Log Page requests to a NVMe-over-Fabrics Discovery
Controller.</p></div>
<div class="paragraph"><p>If no parameters are given, then <em>nvme discover</em> will attempt to
find a /etc/nvme/discovery.conf file to use to supply a list of
Discovery commands to run. If no /etc/nvme/discovery.conf file
exists, the command will quit with an error.</p></div>
<div class="paragraph"><p>Otherwise, a specific Discovery Controller should be specified using the
--transport, --traddr, and if necessary the --trsvcid flags. A Discovery
request will then be sent to the specified Discovery Controller.</p></div>
</div>
</div>
<div class="sect1">
<h2 id="_background">BACKGROUND</h2>
<div class="sectionbody">
<div class="paragraph"><p>The NVMe-over-Fabrics specification defines the concept of a
Discovery Controller that an NVMe Host can query on a fabric
network to discover NVMe subsystems contained in NVMe Targets
which it can connect to on the network. The Discovery Controller
will return Discovery Log Pages that provide the NVMe Host
with specific information (such as network address and unique
subsystem NQN) the NVMe Host can use to issue an
NVMe connect command to connect itself to a storage resource
contained in that NVMe subsystem on the NVMe Target.</p></div>
<div class="paragraph"><p>Note that the base NVMe specification defines the NQN (NVMe Qualified
Name) format which an NVMe endpoint (device, subsystem, etc) must
follow to guarantee a unique name under the NVMe standard.
In particular, the Host NQN uniquely identifies the NVMe Host, and
may be used by the Discovery Controller to control what NVMe Target
resources are allocated to the NVMe Host for a connection.</p></div>
<div class="paragraph"><p>A Discovery Controller has it’s own NQN defined in the NVMe-over-Fabrics
specification, <strong>nqn.2014-08.org.nvmexpress.discovery</strong>. All Discovery
Controllers must use this NQN name. This NQN is used by default by
nvme-cli for the <em>discover</em> command.</p></div>
</div>
</div>
<div class="sect1">
<h2 id="_options">OPTIONS</h2>
<div class="sectionbody">
<div class="dlist"><dl>
<dt class="hdlist1">
-t <trtype>
</dt>
<dt class="hdlist1">
--transport=<trtype>
</dt>
<dd>
<p>
This field specifies the network fabric being used for
a NVMe-over-Fabrics network. Current string values include:
</p>
<div class="tableblock">
<table rules="all"
width="100%"
frame="border"
cellspacing="0" cellpadding="4">
<col width="50%" />
<col width="50%" />
<tbody>
<tr>
<td align="left" valign="top"><p class="table">Value</p></td>
<td align="left" valign="top"><p class="table">Definition</p></td>
</tr>
<tr>
<td align="left" valign="top"><p class="table">rdma</p></td>
<td align="left" valign="top"><p class="table">The network fabric is an rdma network (RoCE, iWARP, Infiniband, basic rdma, etc)</p></td>
</tr>
<tr>
<td align="left" valign="top"><p class="table">fc</p></td>
<td align="left" valign="top"><p class="table"><strong>WIP</strong> The network fabric is a Fibre Channel network.</p></td>
</tr>
<tr>
<td align="left" valign="top"><p class="table">tcp</p></td>
<td align="left" valign="top"><p class="table">The network fabric is a TCP/IP network.</p></td>
</tr>
<tr>
<td align="left" valign="top"><p class="table">loop</p></td>
<td align="left" valign="top"><p class="table">Connect to a NVMe over Fabrics target on the local host</p></td>
</tr>
</tbody>
</table>
</div>
</dd>
<dt class="hdlist1">
-n <subnqn>
</dt>
<dt class="hdlist1">
--nqn <subnqn>
</dt>
<dd>
<p>
This field specifies the name for the NVMe subsystem to connect to.
</p>
</dd>
<dt class="hdlist1">
-a <traddr>
</dt>
<dt class="hdlist1">
--traddr=<traddr>
</dt>
<dd>
<p>
This field specifies the network address of the Discovery Controller.
For transports using IP addressing (e.g. rdma) this should be an
IP-based address (ex. IPv4).
</p>
</dd>
<dt class="hdlist1">
-s <trsvcid>
</dt>
<dt class="hdlist1">
--trsvcid=<trsvcid>
</dt>
<dd>
<p>
This field specifies the transport service id. For transports using IP
addressing (e.g. rdma) this field is the port number. By default, the IP
port number for the RDMA transport is 4420.
</p>
</dd>
<dt class="hdlist1">
-w <traddr>
</dt>
<dt class="hdlist1">
--host-traddr=<traddr>
</dt>
<dd>
<p>
This field specifies the network address used on the host to connect
to the Controller. For TCP, this sets the source address on the socket.
</p>
</dd>
<dt class="hdlist1">
-f <iface>
</dt>
<dt class="hdlist1">
--host-iface=<iface>
</dt>
<dd>
<p>
This field specifies the network interface used on the host to connect
to the Controller (e.g. IP eth1, enp2s0, enx78e7d1ea46da). This forces
the connection to be made on a specific interface instead of letting
the system decide.
</p>
</dd>
<dt class="hdlist1">
-q <hostnqn>
</dt>
<dt class="hdlist1">
--hostnqn=<hostnqn>
</dt>
<dd>
<p>
Overrides the default host NQN that identifies the NVMe Host.
If this option is not specified, the default is read from
/etc/nvme/hostnqn first. If that does not exist, the
autogenerated NQN value from the NVMe Host kernel module is used next.
</p>
</dd>
<dt class="hdlist1">
-I <hostid>
</dt>
<dt class="hdlist1">
--hostid=<hostid>
</dt>
<dd>
<p>
UUID(Universally Unique Identifier) to be discovered which should be
formatted.
</p>
</dd>
<dt class="hdlist1">
-r <filename>
</dt>
<dt class="hdlist1">
--raw=<filename>
</dt>
<dd>
<p>
This field will take the output of the <em>nvme discover</em> command
and dump it to a raw binary file. By default <em>nvme discover</em> will
dump the output to stdout.
</p>
</dd>
<dt class="hdlist1">
-d <device>
</dt>
<dt class="hdlist1">
--device=<device>
</dt>
<dd>
<p>
This field takes a device as input. It must be a persistent device
associated with a Discovery Controller previously created by the
command "connect-all" or "discover". <device> follows the format
nvme*, eg. nvme0, nvme1.
</p>
</dd>
<dt class="hdlist1">
-J <filename>
</dt>
<dt class="hdlist1">
--config=<filename>
</dt>
<dd>
<p>
Use the specified JSON configuration file instead of the
default /etc/nvme/config.json file or <em>none</em> to not read in
an existing configuration file. The JSON configuration file
format is documented in
<a href="https://github.com/linux-nvme/libnvme/blob/master/doc/config-schema.json">https://github.com/linux-nvme/libnvme/blob/master/doc/config-schema.json</a>
</p>
</dd>
<dt class="hdlist1">
-k <#>
</dt>
<dt class="hdlist1">
--keep-alive-tmo=<#>
</dt>
<dd>
<p>
Overrides the default keep alive timeout (in seconds). This
option will be ignored for discovery, and it is only
implemented for completeness.
</p>
</dd>
<dt class="hdlist1">
-c <#>
</dt>
<dt class="hdlist1">
--reconnect-delay=<#>
</dt>
<dd>
<p>
Overrides the default delay (in seconds) before reconnect is attempted
after a connect loss.
</p>
</dd>
<dt class="hdlist1">
-l <#>
</dt>
<dt class="hdlist1">
--ctrl-loss-tmo=<#>
</dt>
<dd>
<p>
Overrides the default controller loss timeout period (in seconds).
</p>
</dd>
<dt class="hdlist1">
-i <#>
</dt>
<dt class="hdlist1">
--nr-io-queues=<#>
</dt>
<dd>
<p>
Overrides the default number of I/O queues create by the driver.
This option will be ignored for the discovery, and it is only
implemented for completeness.
</p>
</dd>
<dt class="hdlist1">
-W <#>
</dt>
<dt class="hdlist1">
--nr-write-queues=<#>
</dt>
<dd>
<p>
Adds additional queues that will be used for write I/O.
</p>
</dd>
<dt class="hdlist1">
-P <#>
</dt>
<dt class="hdlist1">
--nr-poll-queues=<#>
</dt>
<dd>
<p>
Adds additional queues that will be used for polling latency sensitive I/O.
</p>
</dd>
<dt class="hdlist1">
-Q <#>
</dt>
<dt class="hdlist1">
--queue-size=<#>
</dt>
<dd>
<p>
Overrides the default number of elements in the I/O queues created
by the driver which can be found at drivers/nvme/host/fabrics.h.
This option will be ignored for the discovery, and it is only
implemented for completeness.
</p>
</dd>
<dt class="hdlist1">
--keyring=<#>
</dt>
<dd>
<p>
Keyring for TLS key lookup.
</p>
</dd>
<dt class="hdlist1">
--tls_key=<#>
</dt>
<dd>
<p>
TLS key for the connection (TCP).
</p>
</dd>
<dt class="hdlist1">
-g
</dt>
<dt class="hdlist1">
--hdr-digest
</dt>
<dd>
<p>
Generates/verifies header digest (TCP).
</p>
</dd>
<dt class="hdlist1">
-G
</dt>
<dt class="hdlist1">
--data-digest
</dt>
<dd>
<p>
Generates/verifies data digest (TCP).
</p>
</dd>
<dt class="hdlist1">
-p
</dt>
<dt class="hdlist1">
--persistent
</dt>
<dd>
<p>
Don’t remove the discovery controller after retrieving the discovery
log page.
</p>
</dd>
<dt class="hdlist1">
--tls
</dt>
<dd>
<p>
Enable TLS encryption (TCP).
</p>
</dd>
<dt class="hdlist1">
--concat
</dt>
<dd>
<p>
Enable secure concatenation (TCP).
</p>
</dd>
<dt class="hdlist1">
--quiet
</dt>
<dd>
<p>
Suppress already connected errors.
</p>
</dd>
<dt class="hdlist1">
-O
</dt>
<dt class="hdlist1">
--dump-config
</dt>
<dd>
<p>
Print out resulting JSON configuration file to stdout.
</p>
</dd>
<dt class="hdlist1">
-o <fmt>
</dt>
<dt class="hdlist1">
--output-format=<fmt>
</dt>
<dd>
<p>
Set the reporting format to <em>normal</em>, <em>json</em> or <em>binary</em>. Only one
output format can be used at a time.
</p>
</dd>
<dt class="hdlist1">
--force
</dt>
<dd>
<p>
Disable the built-in persistent discover connection rules.
Combined with --persistent flag, always create new
persistent discovery connection.
</p>
</dd>
<dt class="hdlist1">
--nbft
</dt>
<dd>
<p>
Only look at NBFT tables
</p>
</dd>
<dt class="hdlist1">
--no-nbft
</dt>
<dd>
<p>
Do not look at NBFT tables
</p>
</dd>
<dt class="hdlist1">
--nbft-path=<STR>
</dt>
<dd>
<p>
Use a user-defined path to the NBFT tables
</p>
</dd>
<dt class="hdlist1">
--context <STR>
</dt>
<dd>
<p>
Set the execution context to <STR>. This allows to coordinate
the management of the global resources.
</p>
</dd>
<dt class="hdlist1">
-o <fmt>
</dt>
<dt class="hdlist1">
--output-format=<fmt>
</dt>
<dd>
<p>
Set the reporting format to <em>normal</em>, <em>json</em> or <em>binary</em>. Only one
output format can be used at a time.
</p>
</dd>
<dt class="hdlist1">
-v
</dt>
<dt class="hdlist1">
--verbose
</dt>
<dd>
<p>
Increase the information detail in the output.
</p>
</dd>
</dl></div>
</div>
</div>
<div class="sect1">
<h2 id="_examples">EXAMPLES</h2>
<div class="sectionbody">
<div class="ulist"><ul>
<li>
<p>
Query the Discover Controller with IP4 address 192.168.1.3 for all
resources allocated for NVMe Host name host1-rogue-nqn on the RDMA network.
Port 4420 is used by default:
</p>
<div class="listingblock">
<div class="content">
<pre><code># nvme discover --transport=rdma --traddr=192.168.1.3 \
--hostnqn=host1-rogue-nqn</code></pre>
</div></div>
</li>
<li>
<p>
Issue a <em>nvme discover</em> command using the default system defined NBFT tables:
</p>
<div class="listingblock">
<div class="content">
<pre><code># nvme discover --nbft</code></pre>
</div></div>
</li>
<li>
<p>
Issue a <em>nvme discover</em> command with a user-defined path for the NBFT table:
</p>
<div class="listingblock">
<div class="content">
<pre><code># nvme discover --nbft-path=/sys/firmware/acpi/tables/NBFT1</code></pre>
</div></div>
</li>
<li>
<p>
Issue a <em>nvme discover</em> command using a /etc/nvme/discovery.conf file:
</p>
<div class="listingblock">
<div class="content">
<pre><code># Machine default 'nvme discover' commands. Query the
# Discovery Controller's two ports (some resources may only
# be accessible on a single port). Note an official
# nqn (Host) name defined in the NVMe specification is being used
# in this example.
-t rdma -a 192.168.69.33 -s 4420 -q nqn.2014-08.com.example:nvme:nvm-subsystem-sn-d78432
-t rdma -a 192.168.1.4 -s 4420 -q nqn.2014-08.com.example:nvme:nvm-subsystem-sn-d78432
At the prompt type "nvme discover".</code></pre>
</div></div>
</li>
</ul></div>
</div>
</div>
<div class="sect1">
<h2 id="_see_also">SEE ALSO</h2>
<div class="sectionbody">
<div class="paragraph"><p>nvme-connect(1)
nvme-connect-all(1)</p></div>
</div>
</div>
<div class="sect1">
<h2 id="_authors">AUTHORS</h2>
<div class="sectionbody">
<div class="paragraph"><p>This was written by <a href="mailto:james.p.freyensee@intel.com">Jay Freyensee</a></p></div>
</div>
</div>
<div class="sect1">
<h2 id="_nvme">NVME</h2>
<div class="sectionbody">
<div class="paragraph"><p>Part of the nvme-user suite</p></div>
</div>
</div>
</div>
<div id="footnotes"><hr /></div>
<div id="footer">
<div id="footer-text">
Last updated
2025-11-21 00:00:00 UTC
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</div>
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