Date: Wed, 31 Jul 2024 07:36:32 -0700 From: Mark Millard <marklmi@yahoo.com> To: Steve O'Hara-Smith <steve@sohara.org> Cc: Nuno Teixeira <eduardo@freebsd.org>, FreeBSD ARM List <freebsd-arm@freebsd.org> Subject: Re: M.2 storage expansion for RPI 4 (and maybe other boards) Message-ID: <147B31D2-D2B4-47B6-B62B-A391AF9C6421@yahoo.com> In-Reply-To: <20240731151801.9e00f0eeae06979a2d11a93d@sohara.org> References: <CAFDf7U%2BEyTF_GWzhgHRGJ58LsJXXd%2BWEnj9zVZF1a20X49yXaQ@mail.gmail.com> <20240731151801.9e00f0eeae06979a2d11a93d@sohara.org>
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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: >=20 >> Hello all, >>=20 >> =46rom bsdnow I've read about a M.2 expansion board that I'm looking = for. >> ( https://www.bsdnow.tv/569?utm_source=3Dbsdweekly ) >>=20 >> 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. >=20 > 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. >=20 > 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). >=20 >> Currently using a USB3 external SSD disk, should I expect a great >> performance improvement? >=20 > 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=20= >=20 > - 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. =3D=3D=3D Mark Millard marklmi at yahoo.com
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