How to enable trim in RAID?

Question

RAID

There is a fairly loaded database server with SSD disks and a raid controller LSI9260-8i. Recently, they began to notice slowdowns in work, it turned out that this was a problem with the disks. There is a constant queue to them, but at the same time the recording speed is real 50-60mb / s. And when you start copying, the speed is 500mb/s, but quickly rolls down to 60. When mysql works with disks, the speed does not rise higher. Those. as I understand it, when the buffer fills up in ssd and it starts overwriting cells, the speed drops sharply. I tried to connect one disk directly and did not see any problems with it, apparently the trim command worked and the controller always writes to the prepared cells. After googling, I found out that trim doesn't work at all on raid arrays. What if you need a raid?