1NVME-DISCOVER(1) NVMe Manual NVME-DISCOVER(1)
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6 nvme-discover - Send Get Log Page request to Discovery Controller.
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9 nvme discover
10 [--transport=<trtype> | -t <trtype>]
11 [--nqn=<subnqn> | -n <subnqn>]
12 [--traddr=<traddr> | -a <traddr>]
13 [--trsvcid=<trsvcid> | -s <trsvcid>]
14 [--host-traddr=<traddr> | -w <traddr>]
15 [--host-iface=<iface> | -f <iface>]
16 [--hostnqn=<hostnqn> | -q <hostnqn>]
17 [--hostid=<hostid> | -I <hostid>]
18 [--raw=<filename> | -r <filename>]
19 [--device=<device> | -d <device>]
20 [--cfg-file=<cfg> | -C <cfg> ]
21 [--keep-alive-tmo=<sec> | -k <sec>]
22 [--reconnect-delay=<#> | -c <#>]
23 [--ctrl-loss-tmo=<#> | -l <#>]
24 [--hdr_digest | -g]
25 [--data_digest | -G]
26 [--nr-io-queues=<#> | -i <#>]
27 [--nr-write-queues=<#> | -W <#>]
28 [--nr-poll-queues=<#> | -P <#>]
29 [--queue-size=<#> | -Q <#>]
30 [--persistent | -p]
31 [--quiet | -S]
32 [--dump-config | -O]
33 [--output-format=<fmt> | -o <fmt>]
34 [--force]
35
37 Send one or more Get Log Page requests to a NVMe-over-Fabrics Discovery
38 Controller.
39 If no parameters are given, then nvme discover will attempt to find a
41 /etc/nvme/discovery.conf file to use to supply a list of Discovery
42 commands to run. If no /etc/nvme/discovery.conf file exists, the
43 command will quit with an error.
44 Otherwise, a specific Discovery Controller should be specified using
46 the --transport, --traddr, and if necessary the --trsvcid flags. A
47 Diѕcovery request will then be sent to the specified Discovery
48 Controller.
49
51 The NVMe-over-Fabrics specification defines the concept of a Discovery
52 Controller that an NVMe Host can query on a fabric network to discover
53 NVMe subsystems contained in NVMe Targets which it can connect to on
54 the network. The Discovery Controller will return Discovery Log Pages
55 that provide the NVMe Host with specific information (such as network
56 address and unique subsystem NQN) the NVMe Host can use to issue an
57 NVMe connect command to connect itself to a storage resource contained
58 in that NVMe subsystem on the NVMe Target.
59 Note that the base NVMe specification defines the NQN (NVMe Qualified
61 Name) format which an NVMe endpoint (device, subsystem, etc) must
62 follow to guarantee a unique name under the NVMe standard. In
63 particular, the Host NQN uniquely identifies the NVMe Host, and may be
64 used by the the Discovery Controller to control what NVMe Target
65 resources are allocated to the NVMe Host for a connection.
66 A Discovery Controller has it’s own NQN defined in the
68 NVMe-over-Fabrics specification, nqn.2014-08.org.nvmexpress.discovery.
69 All Discovery Controllers must use this NQN name. This NQN is used by
70 default by nvme-cli for the discover command.
71
73 -t <trtype>, --transport=<trtype>
74 This field specifies the network fabric being used for a
75 NVMe-over-Fabrics network. Current string values include:
76 ┌──────┬────────────────────────────┐
78 │Value │ Definition │
79 ├──────┼────────────────────────────┤
80 │rdma │ The network fabric is an │
81 │ │ rdma network (RoCE, iWARP, │
82 │ │ Infiniband, basic rdma, │
83 │ │ etc) │
84 ├──────┼────────────────────────────┤
85 │fc │ WIP The network fabric is │
86 │ │ a Fibre Channel network. │
87 ├──────┼────────────────────────────┤
88 │tcp │ The network fabric is a │
89 │ │ TCP/IP network. │
90 ├──────┼────────────────────────────┤
91 │loop │ Connect to a NVMe over │
92 │ │ Fabrics target on the │
93 │ │ local host │
94 └──────┴────────────────────────────┘
95 -n <subnqn>, --nqn <subnqn>
97 This field specifies the name for the NVMe subsystem to connect to.
98 -a <traddr>, --traddr=<traddr>
100 This field specifies the network address of the Discovery
101 Controller. For transports using IP addressing (e.g. rdma) this
102 should be an IP-based (ex. IPv4) address.
103 -s <trsvcid>, --trsvcid=<trsvcid>
105 This field specifies the transport service id. For transports using
106 IP addressing (e.g. rdma) this field is the port number. By
107 default, the IP port number for the RDMA transport is 4420.
108 -w <traddr>, --host-traddr=<traddr>
110 This field specifies the network address used on the host to
111 connect to the Controller. For TCP, this sets the source address on
112 the socket.
113 -f <iface>, --host-iface=<iface>
115 This field specifies the network interface used on the host to
116 connect to the Controller (e.g. IP eth1, enp2s0, enx78e7d1ea46da).
117 This forces the connection to be made on a specific interface
118 instead of letting the system decide.
119 -q <hostnqn>, --hostnqn=<hostnqn>
121 Overrides the default host NQN that identifies the NVMe Host. If
122 this option is not specified, the default is read from
123 /etc/nvme/hostnqn first. If that does not exist, the autogenerated
124 NQN value from the NVMe Host kernel module is used next.
125 -I <hostid>, --hostid=<hostid>
127 UUID(Universally Unique Identifier) to be discovered which should
128 be formatted.
129 -r <filename>, --raw=<filename>
131 This field will take the output of the nvme discover command and
132 dump it to a raw binary file. By default nvme discover will dump
133 the output to stdout.
134 -d <device>, --device=<device>
136 This field takes a device as input. Device is in the format of
137 nvme*, eg. nvme0, nvme1
138 -C <cfg>, --config-file=<cfg>
140 Use the specified JSON configuration file instead of the default
141 /etc/nvme/config.json file or none to not read in an existing
142 configuration file. The JSON configuration file format is
143 documented in
144 https://github.com/linux-nvme/libnvme/doc/config-schema.json
145 -k <#>, --keep-alive-tmo=<#>
147 Overrides the default dealy (in seconds) for keep alive. This
148 option will be ignored for the discovery, and it is only
149 implemented for completeness.
150 -c <#>, --reconnect-delay=<#>
152 Overrides the default delay (in seconds) before reconnect is
153 attempted after a connect loss.
154 -l <#>, --ctrl-loss-tmo=<#>
156 Overrides the default controller loss timeout period (in seconds).
157 -g, --hdr_digest
159 Generates/verifies header digest (TCP).
160 -G, --data_digest
162 Generates/verifies data digest (TCP).
163 -i <#>, --nr-io-queues=<#>
165 Overrides the default number of I/O queues create by the driver.
166 This option will be ignored for the discovery, and it is only
167 implemented for completeness.
168 -W <#>, --nr-write-queues=<#>
170 Adds additional queues that will be used for write I/O.
171 -P <#>, --nr-poll-queues=<#>
173 Adds additional queues that will be used for polling latency
174 sensitive I/O.
175 -Q <#>, --queue-size=<#>
177 Overrides the default number of elements in the I/O queues created
178 by the driver which can be found at drivers/nvme/host/fabrics.h.
179 This option will be ignored for the discovery, and it is only
180 implemented for completeness.
181 -p, --persistent
183 Persistent discovery connection.
184 -S, --quiet
186 Suppress already connected errors.
187 -O, --dump-config
189 Print out resulting JSON configuration file to stdout.
190 -o <format>, --output-format=<format>
192 Set the reporting format to normal, json, or binary. Only one
193 output format can be used at a time.
194 --force
196 Disable the built-in persitent discover connection rules. Combined
197 with --persistent flag, always create new persistent discovery
198 connection.
199
201 • Query the Discover Controller with IP4 address 192.168.1.3 for all
202 resources allocated for NVMe Host name host1-rogue-nqn on the RDMA
203 network. Port 4420 is used by default:
204 # nvme discover --transport=rdma --traddr=192.168.1.3 \
206 --hostnqn=host1-rogue-nqn
207 • Issue a nvme discover command using a /etc/nvme/discovery.conf
209 file:
210 # Machine default 'nvme discover' commands. Query the
212 # Discovery Controller's two ports (some resources may only
213 # be accessible on a single port). Note an official
214 # nqn (Host) name defined in the NVMe specification is being used
215 # in this example.
216 -t rdma -a 192.168.69.33 -s 4420 -q nqn.2014-08.com.example:nvme:nvm-subsystem-sn-d78432
217 -t rdma -a 192.168.1.4 -s 4420 -q nqn.2014-08.com.example:nvme:nvm-subsystem-sn-d78432
218 At the prompt type "nvme discover".
220
222 nvme-connect(1) nvme-connect-all(1)
223
225 This was written by Jay Freyensee[1]
226
228 Part of the nvme-user suite
229
231 1. Jay Freyensee
232 mailto:james.p.freyensee@intel.com
233NVMe 04/11/2022 NVME-DISCOVER(1)