keepalive.sh

#!/bin/bash
if [[ -z "$1" ]];then echo "You forgot to include a pool/dataset name dummy.  Fix that, then try again." ; exit 1 ; fi  #rectify incorrect usage
# keepalive.sh <poolname>
## Takes a pool name as the first and only parameter.
#
# Config:
#
MYNET="lan.killermist"
# reverse order domain suffix.  In this case, torrents.killermist.lan = lan.killermist
#
ZFSVAR="keepalive"
# An arbitrary ZFS variable suffix that shouldn't conflict with anything
#
# These will be combined into "$MYNET":"$ZFSVAR",
# which in this case will be "lan.killermist:keepalive",
# which should not conflict with any other variable used by any other bit of automation known

## Every 20 seconds, sets the variable "$MYNET":"$ZFSVAR" with the current date/time in the
## (it is the least intrusive thing I could think of that is guaranteed to work)
## This commit to the pool will inhibit any possibility of the pool spinning down.
## When the pool disappears (it has been exported), the while condition fails.
## This breaking the loop, and the script ends.

while zfs set "$MYNET":"$ZFSVAR"=$(date +%F--%X) "$1"
do sleep 20
done