Re: M.2 storage expansion for RPI 4 (and maybe other boards)
Date: Wed, 31 Jul 2024 14:36:32 UTC
On Jul 31, 2024, at 07:18, Steve O'Hara-Smith <steve@sohara.org> wrote: > On Wed, 31 Jul 2024 13:39:48 +0100 > Nuno Teixeira <eduardo@freebsd.org> wrote: > >> Hello all, >> >> From bsdnow I've read about a M.2 expansion board that I'm looking for. >> ( https://www.bsdnow.tv/569?utm_source=bsdweekly ) >> >> The board is https://geekworm.com/products/x862 that it is compatible with >> M.2 NGFF SATA SSDs only, not compatible with NVMe M.2 SSDs, so disk should >> be choosed carefully. > > M2 SATA is just SATA in a different package it is no faster than > any other SATA drive and seems to be on the way out. It was mostly about > making laptop drives smaller. I would avoid it IIWY. > > M2 NVME over PCI-e OTOH is capable of blisteringly fast speeds, the > PCI-e 3 ones serving my /home mirror hit nearly 3GB/s and they're > considered slow ones - fast ones claim over 7GB/s (yes bytes not bits). > >> Currently using a USB3 external SSD disk, should I expect a great >> performance improvement? > > Probably not with M2-SATA - USB-3 is pretty quick. M2 NVME OTOH > will beat anything else by a very healthy margin. Things to watch for > > - PCI-e level and number of lanes needed - make sure the latter matches your > slots. The speed will be determined by the lowest PCI-e level and the > number of lanes. Most M2-NVME drives require four lanes. > - Four slot M2 NVME PCI-e x16 cards usually require a sixteen lane slot with > bifurcation support to four sets of four lanes. The ones that don't cram > everything down four lanes. > - Some M2 slots on motherboards are only single lane - it seems strange to > think of 7-800MB/s as slow but that's how it struck me when I met one. The specified system context was "RPI 4" as the primary example. RPi4B's do not have PCI-e slots. === Mark Millard marklmi at yahoo.com