Similar to badblocks, except writes to multiple disks at once
As this is written in Python, getting the dependencies installed is a bit of a pain:
$ git clone https://github.com/justinclift/multi_disk_tester
$ cd multi_disk_tester
$ python3 -m venv stuff
$ . stuff/bin/activate
$ pip3 install poetry
$ poetry install
Because the code doesn't handle sudo at all, you'll need to ensure your user has permission to write to the disk devices first:
$ sudo chmod o+rw /dev/zvol/rpool/disktests1 /dev/zvol/rpool/disktests2
$ ./multi_test.py -d /dev/zvol/rpool/disktests1 -d /dev/zvol/rpool/disktests2