Review on Synology M 2 Adapter Card M2D18 by Lex Ismael

I've deployed two of these. Ideal for designing. This is an IDT/Renasas 24 lane PCI switch, part number 89HPES24T6G2, and a Marvel dual port SATA controller on the back panel. This is an 8-lane physical and logical connection with speeds up to PCIe 2.0. Each M.2 slot supports any M-Key SSD as long as they are both SATA or both NVMe. In NVMe mode, this is a 4-lane PCIe slot. In total, it occupies 16 of the 24 lanes, which means that the PCIe switch is never overloaded. Linux automatically supports this switch, but the version you're running sets the tone. When this card was servicing two NVMe drives, I could see them, but as soon as I wrote to one of them, there were I/O drops, timeouts, and freezes before powering off. Two such cards, 4 NVMe drives in total. Not a bad machine. I am using OVM server 3.4.6.2. Unplugging the NVMe drives and plugging them into each drive connector works fine, so it's specific to the PCIe switch. There is an ASM card on the market that does the same thing and probably works better. I didn't try. There is a powerful raid map that some people have had success with. Research appears that Linux and FreeBSD are still working on the code for such bugs. Maybe it will work with a newer version, but it doesn't help for enterprise linux distributions today. Synology has special hardware and special OS builds to deal with this problem, and some of them may slightly reduce the performance of each line to the kernel, TRIM command processing, reset command processing, etc. Maybe in OVM 4 and RHEL 8 we'll see something stable, but today I just can't use them on a standalone Linux system. However, this is my limitation. The equipment is excellent. The installation of the radiator is well thought out. The screw set is perfect and comes with both low profile and full profile backplates. It looks clean, well designed and just great hardware. Plus the price is great for what it is. It's very competitive. If you have a supported Synology storage array or are running the latest version of Linux or are using SATA M-Key drives, this might be a great option for you.