zfs/cmd/zpool/zpool.d/iostat

#!/bin/sh
#
# Display most relevant iostat bandwidth/latency numbers.  The output is
# dependent on the name of the script/symlink used to call it.
#

helpstr="
iostat:		Show iostat values since boot (summary page).
iostat-1s:	Do a single 1-second iostat sample and show values.
iostat-10s:	Do a single 10-second iostat sample and show values."

script="${0##*/}"
if [ "$1" = "-h" ] ; then
	echo "$helpstr" | grep "$script:" | tr -s '\t' | cut -f 2-
	exit
fi

if [ "$script" = "iostat-1s" ] ; then
	# Do a single one-second sample
	interval=1
	# Don't show summary stats
	brief="yes"
elif [ "$script" = "iostat-10s" ] ; then
	# Do a single ten-second sample
	interval=10
	# Don't show summary stats
	brief="yes"
fi

# shellcheck disable=SC2154
if [ -f "$VDEV_UPATH" ] ; then
	# We're a file-based vdev, iostat doesn't work on us.  Do nothing.
	exit
fi

if [ "$(uname)" = "FreeBSD" ]; then
	out=$(iostat -dKx \
		${interval:+"-w $interval"} \
		${interval:+"-c 1"} \
		"$VDEV_UPATH" | tail -n 2)
else
	out=$(iostat -kx \
		${brief:+"-y"} \
		${interval:+"$interval"} \
		${interval:+"1"} \
		"$VDEV_UPATH" | grep -v '^$' | tail -n 2)
fi


# Sample output (we want the last two lines):
#
# Linux 2.6.32-642.13.1.el6.x86_64 (centos68) 	03/09/2017 	_x86_64_	(6 CPU)
#
# avg-cpu:  %user   %nice %system %iowait  %steal   %idle
#           0.00    0.00    0.00    0.00    0.00  100.00
#
# Device:         rrqm/s   wrqm/s     r/s     w/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await r_await w_await  svctm  %util
# sdb               0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00    0.00    0.00   0.00   0.00
#

# Get the column names
cols=$(echo "$out" | head -n 1)

# Get the values and tab separate them to make them cut-able.
vals=$(echo "$out" | tail -n 1 | tr -s '[:space:]' '\t')

i=0
for col in $cols ; do
	i=$((i+1))
	# Skip the first column since it's just the device name
	if [ "$i" -eq 1 ]; then
		continue
	fi

	# Get i'th value
	val=$(echo "$vals" | cut -f "$i")
	echo "$col=$val"
done