On Wednesday, 26 February 2025 14:43:41 Greenwich Mean Time Dale wrote: > Rich Freeman wrote: > > On Tue, Feb 25, 2025 at 12:26 PM Dale <rdalek1...@gmail.com> wrote: > >> I'm pretty sure you mentioned this once before in one of my older > >> threads. I can't find it tho. I use PCIe x1 cards to connect my SATA > >> drives for my video collection and such. You mentioned once what the > >> bandwidth was for that setup and how many drives it would take to pretty > >> much max it out. Right now, I have one card for two sets of LVs. One > >> LV has four drives and the other has three. What would be the limiting > >> factor on that, the drives, the PCIe bus or something else? > > > > It depends on the PCIe revision, and of course whether the controller > > actually maxes it out. > > > > 1x PCIe v3 can do 0.985GB/s total. That's about 5 HDDs if they're > > running sequentially, and again assumes that your controller can > > actually handle all that data. For each generation of PCIe > > forward/backwards either double/halve the transfer rate. The > > interface works at the version of PCIe supported by both the > > motherboard+CPU and the adapter card. > > > > If you're talking about HDDs in practice the HDDs are probably still > > the bottleneck. If these were SATA SSDs then odds are that the PCIe > > lane is limiting things, because I doubt this is an all-v5 setup. > > > > https://en.wikipedia.org/wiki/PCI_Express#History_and_revisions > > > > The big advantage of NVMe isn't so much the bandwidth as the IOPS, > > though both benefit. Those run at full PCIe 4x interface speed per > > drive, but of course you need 4 lanes per drive for this, which is > > hard to obtain on consumer motherboards at any scale. > > This I think is what I needed. As it is, I'm most likely not maxing > anything out, yet. The drives for Data, torrent stuff, stays pretty > busy. Mostly reading. My other set of drives, videos, isn't to busy > most of the time. A few MBs/sec or something, playing videos type > reading. Still, next time I power down, I may stick that second card in > and divide things up a bit. Might benefit if those cards aren't to great. > > I did copy this info and stuck in in a text file so I don't have to dig > for it again, or ask again. ;-) > > Thanks. > > Dale > > :-) :-)
The other thing to straighten out, already hinted at by Rich et al., is an NVMe M.2 card in a USB 3 enclosure won't be able to maximise its SSD transfer rates. To do this it will require a Thunderbolt connector and a corresponding Thenderbolt PC port, which will connect it internally to the computer's PCIe bus, rather than USB/SATA. Hence a previous comment questioning the perceived value of paying for a NVMe SSD M.2 form factor within a USB enclosure. It won't really derive much if any performance benefit compared to a *good* quality USB 3 flash drive (UFD), which can be sourced at a much lower price point. External storage medium, transfer protocol, device controller, PC bus and cables/connectors/ports, will all have to have aligned generations of technology and standards, if you expect to make most of their advertised transfer speeds. Otherwise you'll be stuck at some component of a lower performance providing a bottleneck to your aspirations. ;-) Sometime ago I bought a SanDisk 1TB Extreme Portable SSD, which has a USB-C connector and a USB 3.2 Gen 2 controller as a replacement for a flaky USB 3.0 stick. It is slightly bigger than a small UFD and more expensive than the cheaper UFD offerings, but the faster speeds more than compensate for it. At the time I bought it, external NVMe M.2 drives were too expensive and I only had USB 3.0 ports anyway. So in my use case it was offering the best bang for my buck.
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