Subj : Re: Pi5 M.2 HAT To : Pancho From : Theo Date : Thu Oct 31 2024 12:42:19 Pancho wrote: > I have three 2242 NVMe, they work fine, apart from some versions of > U-Boot boot loader (They actually worked in older versions, then stopped > working). A couple of those are 256GB from a couple of years ago, due to > the price low differential I would buy 512GB now. > > I'm thinking of getting a M.2 NVMe adapter for my rPI5, I'll probably > get a Pimoroni one, because it take standard 2280 drives. Best to go > with the flow. Agreed, if you don't need the small size then I'd go 2280 - plenty more to choose from. > > I think they've got them around the wrong way. Their ODM Biwin's 2230 has > > more read than write IOPS: > > https://droix.co.uk/product/biwin-2230/ > > > > Yeahbut... > > > > 650K IOPS Max. Random Read 4K > 800K IOPS Max. Random Write 4K > > > But as I said, I don't really understand what IOPS means. The same > device quotes a faster Max Read than Max Write (presumably sustained > read/write). 4K random read test: If the disc contains N blocks of size 4K Repeat: - roll a dice between 0 and N to give you D - read 4K block number D from the disc - throw away the data that came back IOPS = how many times you can do that in a second IOPS is a function of how well the flash and controller can manage an unpredictable workload. It's also a function of transfer speed to some extent - you still need to move the data. That 800K IOPS is 3.2GB/s or 26.2Gbps. The Pi's single PCIe lane is only officially rated at Gen2 or 5Gbps, which puts a hard limit of 4K IOPS of 150K (and PCIe transfers have additional overhead on top of that) A more interesting graph in reviews is 'performance consistency': if you give it a sustained write workload like this, after many minutes eventually the speed falls as all the on-drive buffers fill up. How well engineered it is will show whether it can hold its performance, degrade gradually, hop around erratically, or fall off a cliff. Theo --- SoupGate-Win32 v1.05 * Origin: Agency HUB, Dunedin - New Zealand | Fido<>Usenet Gateway (3:770/3) .