I am currently building a RaidZ2 with Ubuntu for scientific data storage for my PhD in physics and some VM use (cf. this thread (link))
There are 10x 4TB WD RED (CMR) in the RaidZ2 with dedup and lz4 compression as well as a WD Black NVMe for l2arc.
The HDD are connected via a HPE 240 in HBA mode.
In the moment I do not use it primarily for scientific data storage, aside the occasional photo and video storage/editing and VM use.
Later I will also use it as NAS but in the moment I access the data only once a day mainly when storing results of number-crunching and loading the new data.
I have come to the conclusion that it would be best to power down the HDD (even after factoring in spin up etc.) So my question is:
What is the best practice for powering down the spinning rust in the RaidZ2 automatically?
Any major caveats?
How to implement that in Ubuntu 20.04?
Thanks a lot for your input!