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Vnetperf

The vnetperf utility measures network performance of database hosts, as well as network latency and throughput for TCP and UDP protocols.

Caution

This utility incurs high network load, which degrades database performance. Do not use this utility on a Vertica production database.

This utility helps identify the following issues:

Low throughput for all hosts or one
High latency for all hosts or one
Bottlenecks between one or more hosts or subnets
Too-low limit on the number of TCP connections that can be established simultaneously
High rates of network packet loss

Syntax

vnetperf [[options](#Options)] [[tests](#Tests)]

Options

--condense

Condenses the log into one JSON entry per line, instead of indented JSON syntax.

--collect-logs

Collects test log files from each host.

--datarate rate

Limits throughput to this rate in MB/s. A rate of 0 loops the tests through several different rates.

Default: 0

--duration seconds

Time limit for each test to run in seconds.

Default: 1

--hosts host-name[,...]

Comma-separated list of host names or IP addresses on which to run the tests. The list must not contain embedded spaces.

--hosts file

File that specifies the hosts on which to run the tests. If you omit this option, then the vnetperf tries to access admintools to identify cluster hosts.

--identity-file file

If using passwordless SSH/SCP access between hosts, then specify the key file used to gain access to the hosts.

--ignore-bad-hosts

If set, runs tests on reachable hosts even if some hosts are not reachable. If you omit this option and a host is unreachable, then no tests are run on any hosts.

--log-dir directory

If --collect-logs is set, specifies the directory in which to place the collected logs.

Default: logs.netperf.<timestamp>

--log-level level

Log level to use, one of the following:

INFO
ERROR
DEBUG
WARN

Default: WARN

--list-tests

Lists the tests that vnetperf can run.

--output-file file

The file to which JSON results are written.

Default: results.<timestamp>.json

--ports port#[,...]

Comma-delimited list of port numbers to use. If only one port number is specified, then the next two numbers in sequence are also used.

Default: 14159,14160,14161

--scp-options 'scp-args'

Specifies one or more standard SCP command line arguments. SCP is used to copy test binaries over to the target hosts.

--ssh-options 'ssh-args'

Specifies one or more standard SSH command line arguments. SSH is used to issue test commands on the target hosts.

--tmp-dir directory

Specifies the temporary directory for vnetperf, where directory must have execute permission on all hosts, and does not include the unsupported characters ", ```, or '.

Default: /tmp (execute permission required)

--vertica-install directory

Indicates that Vertica is installed on each of the hosts, so vnetperf uses test binaries on the target system rather than copying them over with SCP.

Tests

vnetperf can specify one or more of the following tests. If no test is specified, vnetperf runs all tests. Test results are printed for each host.

Test	Description	Results
`latency`	Measures latency from the host that is running the script to other hosts. Hosts with unusually high latency should be investigated further.	Round trip time latency for each host in milliseconds. Clock skew—the difference in time shown by the clock on the target host relative to the host running the utility.
`tcp-throughput`	Tests TCP throughput among hosts.	Date/time and test name Rrate limit in MB/s Tested node Sent and received data in MB/s and bytes Duration of the test in seconds
`udp-throughput`	Tests UDP throughput among hosts

Recommended network performance

Maximum recommended RTT (round-trip time) latency is 1000 microseconds. Ideal RTT latency is 200 microseconds or less. Vertica recommends that clock skew be less than 1 second.
Minimum recommended throughput is 100 MB/s. Ideal throughput is 800 MB/s or more.

Note
UDP throughput can be lower; multiple network switches can adversely affect performance.

Example

$ vnetperf latency tcp-throughput

The maximum recommended rtt latency is 2 milliseconds. The ideal rtt latency is 200 microseconds or less. It is recommended that clock skew be kept to under 1 second.
test              | date                    | node             | index | rtt latency (us)  | clock skew (us)
-------------------------------------------------------------------------------------------------------------------------
latency           | 2022-03-29_10:23:55,739 | 10.20.100.247    | 0     | 49                | 3
latency           | 2022-03-29_10:23:55,739 | 10.20.100.248    | 1     | 272               | -702
latency           | 2022-03-29_10:23:55,739 | 10.20.100.249    | 2     | 245               | 1037

The minimum recommended throughput is 100 MB/s. Ideal throughput is 800 MB/s or more. Note: UDP numbers may be lower, multiple network switches may reduce performance results.
date                    | test              | rate limit (MB/s) | node             | MB/s (sent) | MB/s (rec)  | bytes (sent)        | bytes (rec)         | duration (s)
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
2022-03-29_10:23:55,742 | tcp-throughput    | 32                | 10.20.100.247    | 30.579      | 30.579      | 32112640            | 32112640            | 1.00151
2022-03-29_10:23:55,742 | tcp-throughput    | 32                | 10.20.100.248    | 30.5791     | 30.5791     | 32112640            | 32112640            | 1.0015
2022-03-29_10:23:55,742 | tcp-throughput    | 32                | 10.20.100.249    | 30.5791     | 30.5791     | 32112640            | 32112640            | 1.0015
2022-03-29_10:23:55,742 | tcp-throughput    | 32                | average          | 30.579      | 30.579      | 32112640            | 32112640            | 1.0015
2022-03-29_10:23:57,749 | tcp-throughput    | 64                | 10.20.100.247    | 61.0952     | 61.0952     | 64094208            | 64094208            | 1.00049
2022-03-29_10:23:57,749 | tcp-throughput    | 64                | 10.20.100.248    | 61.096      | 61.096      | 64094208            | 64094208            | 1.00048
2022-03-29_10:23:57,749 | tcp-throughput    | 64                | 10.20.100.249    | 61.0952     | 61.0952     | 64094208            | 64094208            | 1.00049
2022-03-29_10:23:57,749 | tcp-throughput    | 64                | average          | 61.0955     | 61.0955     | 64094208            | 64094208            | 1.00048
2022-03-29_10:23:59,753 | tcp-throughput    | 128               | 10.20.100.247    | 122.131     | 122.131     | 128122880           | 128122880           | 1.00046
2022-03-29_10:23:59,753 | tcp-throughput    | 128               | 10.20.100.248    | 122.132     | 122.132     | 128122880           | 128122880           | 1.00046
2022-03-29_10:23:59,753 | tcp-throughput    | 128               | 10.20.100.249    | 122.132     | 122.132     | 128122880           | 128122880           | 1.00046
2022-03-29_10:23:59,753 | tcp-throughput    | 128               | average          | 122.132     | 122.132     | 128122880           | 128122880           | 1.00046
2022-03-29_10:24:01,757 | tcp-throughput    | 256               | 10.20.100.247    | 243.819     | 244.132     | 255754240           | 256081920           | 1.00036
2022-03-29_10:24:01,757 | tcp-throughput    | 256               | 10.20.100.248    | 244.125     | 243.282     | 256049152           | 255164416           | 1.00025
2022-03-29_10:24:01,757 | tcp-throughput    | 256               | 10.20.100.249    | 244.172     | 243.391     | 256114688           | 255295488           | 1.00032
2022-03-29_10:24:01,757 | tcp-throughput    | 256               | average          | 244.039     | 243.601     | 255972693           | 255513941           | 1.00031
2022-03-29_10:24:03,761 | tcp-throughput    | 512               | 10.20.100.247    | 337.232     | 485.247     | 355893248           | 512098304           | 1.00645
2022-03-29_10:24:03,761 | tcp-throughput    | 512               | 10.20.100.248    | 446.16      | 231.001     | 467894272           | 242253824           | 1.00013
2022-03-29_10:24:03,761 | tcp-throughput    | 512               | 10.20.100.249    | 349.667     | 409.961     | 368476160           | 432013312           | 1.00497
2022-03-29_10:24:03,761 | tcp-throughput    | 512               | average          | 377.686     | 375.403     | 397421226           | 395455146           | 1.00385
2022-03-29_10:24:05,772 | tcp-throughput    | 640               | 10.20.100.247    | 328.279     | 509.256     | 383975424           | 595656704           | 1.11548
2022-03-29_10:24:05,772 | tcp-throughput    | 640               | 10.20.100.248    | 505.626     | 217.217     | 532250624           | 228655104           | 1.00389
2022-03-29_10:24:05,772 | tcp-throughput    | 640               | 10.20.100.249    | 390.355     | 474.89      | 410812416           | 499777536           | 1.00365
2022-03-29_10:24:05,772 | tcp-throughput    | 640               | average          | 408.087     | 400.454     | 442346154           | 441363114           | 1.04101
2022-03-29_10:24:07,892 | tcp-throughput    | 768               | 10.20.100.247    | 300.5       | 426.762     | 318734336           | 452657152           | 1.01154
2022-03-29_10:24:07,892 | tcp-throughput    | 768               | 10.20.100.248    | 268.252     | 402.891     | 283017216           | 425066496           | 1.00616
2022-03-29_10:24:07,892 | tcp-throughput    | 768               | 10.20.100.249    | 510.569     | 243.649     | 535592960           | 255590400           | 1.00042
2022-03-29_10:24:07,892 | tcp-throughput    | 768               | average          | 359.774     | 357.767     | 379114837           | 377771349           | 1.00604
2022-03-29_10:24:09,911 | tcp-throughput    | 1024              | 10.20.100.247    | 304.545     | 444.261     | 334987264           | 488669184           | 1.049
2022-03-29_10:24:09,911 | tcp-throughput    | 1024              | 10.20.100.248    | 422.246     | 192.773     | 474284032           | 216530944           | 1.07121
2022-03-29_10:24:09,911 | tcp-throughput    | 1024              | 10.20.100.249    | 353.206     | 446.809     | 378732544           | 479100928           | 1.0226
2022-03-29_10:24:09,911 | tcp-throughput    | 1024              | average          | 359.999     | 361.281     | 396001280           | 394767018           | 1.0476
2022-03-29_10:24:11,988 | tcp-throughput    | 2048              | 10.20.100.247    | 343.324     | 414.559     | 387710976           | 468156416           | 1.07697
2022-03-29_10:24:11,988 | tcp-throughput    | 2048              | 10.20.100.248    | 292.44      | 246.254     | 308314112           | 259620864           | 1.00544
2022-03-29_10:24:11,988 | tcp-throughput    | 2048              | 10.20.100.249    | 437.559     | 405.02      | 459145216           | 425000960           | 1.00072
2022-03-29_10:24:11,988 | tcp-throughput    | 2048              | average          | 357.774     | 355.278     | 385056768           | 384259413           | 1.02771

JSON results available at: ./results.2022-03-29_10:23:51,548.json