pick the right raid chunk size

overview and benchmarks

if you are building a 10TB ZFS proof of concept NAS with 1GbE networking, the Intel Optane Memory 32GB M.2 drive is an enormous upgrade over SATA and SAS devices in the sub $100 category if you can live with the lower endurance and reliability ratings.

As we have tested the device and had both it and the M.2 version in our lab for some time, the question is whether it is worthwhile. Since 1PB written would be about the maximum we plan for on low-end storage server equipped with only 10GbE, the Optane 900p/ 905p we see as a better value. They are faster and higher capacity with a lower cost per GB.

from October 2018:
"If you already have an SSD as your main drive and have your games and large files on your mechanical drive, it is still worth getting a second SSD to use as a cache for the mechanical drive. This small investment to get either a 32GB or a 64GB SSD and use it as your hard drive’s cache is going to be worth your money for the performance gains.

In fact, since SSDs are becoming cheaper and cheaper, there should be no reason for you not to get a 64GB SSD to use as a cache memory for your HDD."

“Authority” in this case doesn’t get much better than Matthew Ahrens, one of the cofounders of ZFS at Sun Microsystems and current ZFS developer at Delphix. In the comments to one of my filesystem articles on Ars Technica, Matthew said “There’s nothing special about ZFS that requires/encourages the use of ECC RAM more so than any other filesystem.”