Date: Wed, 31 Jul 2024 15:18:01 +0100 From: Steve O'Hara-Smith <steve@sohara.org> To: Nuno Teixeira <eduardo@freebsd.org> Cc: FreeBSD ARM List <freebsd-arm@freebsd.org> Subject: Re: M.2 storage expansion for RPI 4 (and maybe other boards) Message-ID: <20240731151801.9e00f0eeae06979a2d11a93d@sohara.org> In-Reply-To: <CAFDf7U%2BEyTF_GWzhgHRGJ58LsJXXd%2BWEnj9zVZF1a20X49yXaQ@mail.gmail.com> References: <CAFDf7U%2BEyTF_GWzhgHRGJ58LsJXXd%2BWEnj9zVZF1a20X49yXaQ@mail.gmail.com>
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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. -- Steve O'Hara-Smith <steve@sohara.org>
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