Slow transfer speeds

[HoneyBadger]

I dragged over an old post of mine that explains how the “write throttle” works, but it doesn’t pull apart the issue with different NAND types and SLC caching tricks.

Some Insights (and generalizations) on the OpenZFS Write Throttle

If you’re wondering “why do the writes to my TrueNAS system start off really fast, but slow down after a few seconds?” then this post may help elaborate a little bit on the nature of the OpenZFS “Write Throttle” - the mechanism by which TrueNAS adjusts the incoming rate so that your system is still able to respond to remote requests in a timely manner while not overwhelming your pool disks. The below comments should be considered for users who have made no changes to their tunables. I’ll talk a…