Status of data node. "UP" means OK and "DOWN" means currently not available
ping
double
Data node response in milliseconds during speed test
Arguments
speed_test
If TRUE, use pingr::ping() to perform connection speed
test on each data node. A ping column is appended in returned
data.table which stores each data node response in milliseconds. This
feature needs pingr package already installed. Default: FALSE.
timeout
Timeout for a ping response in seconds. Default: 3.