Model a m.2 nvme

#1

I just got a model a and did not realize the lack of m.2 slot M connector. Without it, It seems that the only option for an SSD would be much slower sata since the spec says the m.2 is only 1 lane. The strange thing is that the radxa m.2 E to M adapter claims to support 4 lanes. Has anyone tried measuring the m.2 slot ssd speed on this board? Maybe someone has tried it on the model b m.2 E slot which I presume is the same. Without this it seems the model a is the same as a raspberry pi for ssd speed, right?

#2

You can buy an NVME HAT from Radxa. Also, as you can use eMMC, unlike on a raspberry pi.

#3

Would the nvme hat be limited to 1 lane on the m.2 e key?

#4

Unfortunately, yes, it is as limited as a WiFi card.

#5

I suppose it’s still theoretically faster than sata over usb 3 by 4x (2GB/s vs 480)

1 Like
#6

Indeed, the M.2 E slot of Rock 5a is PCIe 2.1 with a single lane, so speed is limited to about 500 MB/s, whatever the adapter You connect to it. For a basic SATA SSD, it might be satisfying, but not for a fast nvme drive.
The M.2 M slots of other boards are more interesting, for instance:

  • Rock 3A -> PCIe 3.0 x 2 (max 2 GB/s) - requires specific hat for nvme
  • Rock 4B+ -> PCIe 2.0 x 4 (max 2 GB/s) - requires specific hat for nvme
  • Rock 5B -> PCIe 3.0 x 4 (max 4 GB/s) - suitable for 2280 nvme
#7

So it seems strange to do a Rock 5 model A and drop the M2 M slot from the Model B. But I can see the model A then competing with the model B sales. Maybe going to a 3588S instead of 3588 makes the difference?

#8

Yes, 3588S doesn’t have nearly as many pci-e lanes.

#9

Indeed, the cheaper but cost effective RK3588S is limited compared to its brother/sister chip and explains the main difference in PCIe speeds.
RK3388S is power efficient but Rock 5a board based on this chip shows two major downsides: it allows only limited high speed connectivity by dropping the PCIe M2M slot and only has regular Gigabit ethernet instead on the 2.5 Gbps connector on the Rock 5b. So Rock 5a is nice for CPU hungry tasks but with low speed connectivity while Rock 5b is a nice full feature board for NAS solutions although Radxa does not provide any convincing accessory for the purpose.

#10

This page claims its 2.5GbE Lan. Are you sure it’s 1GbE? https://wiki.radxa.com/Rock5/5a. But all net China confirms what you are saying which is very disappointing seeing I just bought a 2.5GbE Poe switch. https://shop.allnetchina.cn/products/rock5-model-a

#11

I own one sample of both Rock 5a and Rock 5b boards, so unfortunately, I confirm Rock 5a only has a GbE LAN while Rock 5b has 2.5 GbE. This is also confirmed on https://wiki.radxa.com/Rock5/hardware/5a and the more recent page https://radxa.com/rock5a. Please note the wiki is the old site so You should stick to https://radxa.com site for up-to-date information