I have 6x 256gb ssds in a radi array, 4x3tb spinning disks in a raid and 2 10tb in a mirror
all disks check out against 3rd party software when removed and checked for errors, did this and then rebuild each array and reloaded from backup
running an intel dp55wg motherboard with i3 dual core cpu and 8gb ram ssds are using onboard sata and both arrays are on marvell chipset pcie cards
had been running super fast until one pcie card failed and disks disappeared and came back since then its all been a bit of hit and miss as to weather i get a good connection or not
also have dual 1gb network cards in a LAG to a properly configured switch.
all disks are new or within 12 months old raid is through synology and not hardware level raid
I have the 6.2 loader and tried on a different system, all working fine, I may just go for a total rebuild and see what happens