SYNOPSIS

nvme [<global-options>] top [--delay=<seconds> | -d <seconds>]

DESCRIPTION

Shows the subsystems with their I/O rates, refreshed every few seconds, like top(1). Enter shows the namespaces, the paths and the controllers of a subsystem, with their rates, the retries and errors, the multipath failovers and the controller resets and reconnects.

With --output-format=json, takes two samples --delay seconds apart, prints the rates and the counters as one JSON document, and exits. This is the output for scripts and monitoring tools.

The rates come from the block layer statistics of the namespaces and the paths. A rate is per second, a latency is the average time of an I/O in milliseconds, and the utilization is the share of the interval the device was busy. The rates of a subsystem and a controller are the sum of those of their namespaces or paths, the latency and the utilization the highest of them.

OPTIONS

-d <seconds>
--delay=<seconds>

The time between two refreshes, or between the two samples of the JSON output. The default is 1.

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 <fmt>
--output-format=<fmt>

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

--output-format-version=<version>

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

--quiet

Suppress informational messages. Errors are still reported, and --quiet cancels any --verbose for the library log level.

--set-options=<key=value>[,<key=value>…]

Set libnvme library options for this invocation. Supported keys are force-4k, mi-probe-enabled, test-base-dir and test-sysfs-dir.

--timeout=<ms>

Set the timeout for the command in milliseconds. infinite or -1 waits without a time limit (0xffffffff).

-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). A command-line flag always overrides the file.

JSON OUTPUT

The document has the Interval in seconds and a Subsystems array. A subsystem has its Name, NQN, HostNQN, IOPolicy, Model, Serial, Firmware and Type, its Stats, a Namespaces array and a Controllers array.

A namespace of a multipath subsystem has its Name, NSID, the RequeueIO and FailIO counts of the I/O which found no usable path, its Stats and a Paths array. A path has its Name, Controller, ANAState, NUMANodes, Qdepth, the Retries, Failovers and Errors counts and its Stats.

A namespace of a subsystem without multipath has its Name, NSID, Controller, the Retries and Errors counts and its Stats.

A controller has its Name, Transport, Address, State, NUMANode, the number of Paths of a multipath subsystem, the Resets, Reconnects and Errors counts and its Stats.

The Stats of a namespace or a path are ReadIOPS, WriteIOPS, ReadLatencyMs, WriteLatencyMs, ReadBytesPerSec, WriteBytesPerSec, Inflights and UtilPercent. Those of a subsystem or a controller have MaxReadLatencyMs, MaxWriteLatencyMs and MaxUtilPercent instead of the latencies and the utilization, and no Inflights.

A counter or an attribute the kernel does not provide is left out.

EXAMPLES

  • Watch the subsystems, refreshed every 2 seconds: 

    # nvme top --delay=2

  • Print the rates over 5 seconds as JSON: 

    # nvme top --delay=5 --output-format=json

NVME

Part of the nvme-user suite