vnetperf

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

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] [tests]

Options

Option	Description
`--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.
UDP throughput can be lower; multiple network switches can adversely affect performance.

Example