I have an unraid server with 13 4TB drives (one parity) and 9 2TB drives totaling 66TB, of which 44.6TB is already in use. Its running 6.1.9 on a 8 core HP Poliant ML150 G5 with 16GB of ram.
The data is a mixture of video, music, photos, and computer backups across 45+ shares. Docker is used to run various services from sickbeard, sabnzb, syncthing, and plex (and more).
I have tested direct dd's to /mnt/disk* and when booted, but docker not running and I get 100-500MB/s write and 90-180MB/s reads across all the disks. Once I startup docker and plex, this access drop considerably to 30-50MB/s write and 40-90MB/s read. All this is still acceptable. But once Plex (or other service) begins to use the system, access speed both in and outside the host drop down below 2MB/s.
It was not like this 2-3 months ago. In that time we moved to add in the 2TB drives in batches due to the existing 4TB drives filling up.
What information would you need from the host to assist with some kind of investigation?
I am still seeing really crappy performance with just Plex running.