Here is my setup. I have a HP DL380p G8 with an LSI 9205 HBA in IT mode. I am running Ubuntu server 18.04. I configured 4 4TB drives in an RaidZ1 with a Samaung 970 EVO as a cache drive.
Then use MergerFS as transport layer to easily present the pool and any other JBOD drive to my other windows PCs as a single directory via samba.
I used Alex Kretzschmar’s of Self Hosted and his perfect media server series as a template. https://blog.linuxserver.io/2019/07/16/perfect-media-server-2019/
My issue is that I am trying to write data to the zfs pool and I will get full speed for about 30 seconds then it will start to degrade till the transfer drops to kb/s sometimes it will come back up to full speed but it will keep going through the same cycle.
then eventually the transfer will timeout. Let me know what other information would be helpful.