On Thu, Dec 05, 2024 at 10:55:48AM -0500, e...@gmx.us wrote:
How do I tell how many lanes a given drive uses (preferably before purchase)?
It would be buried in the technical docs. I've only seen 4x drives (but I'm sure there may be some cheaper drives with fewer). On the motherboard side it's common to see 2 lanes in some slots for the simple reason that there are a limited number of lanes from the CPU--most people would rather have a slower-connected drive than none at all. Having 2 lanes may not even be a limitation: 2 PCIe v3 lanes are the same speed as 4 v2 lanes. The bandwith to the drive is rarely a bottleneck, especially at the desktop level. For best results plug your drive into the motherboard slot with the largest number of the highest version lanes. A lower version drive can be used in a higher version slot with no penalty, and a higher version drive can be used in a lower version slot but will run each lane at the lower speed and will have half the theoretical performance, or less.
E.g.: my motherboard has something like 4x v5 + 4x v4 + 2x v4 + 4x v3. Let's say I have 2 v4 drives and 1 v3 drive. If I put one v4 drive in the 4x v5 slot, one in the 4x v4 slot, and the v3 drive in the 4x v3 slot, all the drives will operate at their peak efficiency. If I put a 4x v4 drive in the 2x v4 or 4x v3 slot, it will operate at the same lower level (half the peak bandwidth). Also, if I put the v3 drive in the 2x v4 slot it will only be able to use half of its bandwidth, because it will only run at 2x v3 (as it is a v3 drive). Bottom line, it's worth checking the motherboard documentation if you have multiple M.2 slots, but only because it costs nothing to do so.
Yeah, I probably wouldn't be able to tell. It's just geek points. I was thinking it might matter when xferring gigabyte+ files to the media server, but then the bottleneck would either be the CPU encrypting the SSH data, or the network itself.
Yes. Also not many drives can sustain a multi-gigabyte write rate anyway, and if you're just talking bursts most situations won't differentiate between moving 200MB in .1s vs 1s as the write is generally buffered by the OS. So where the peak speed matters on the desktop is mostly in very large reads with no writing, which just don't happen much. Basically game startup, but the game itself is probably not written to depend on 16GB/s because most people wouldn't be able to run it. Once you're beyond the 600MB/s of SATA into any NVMe you've hit the point of diminishing returns.
Is one kind more long-lived than the other?
Not due specifically to the interface. At the same price point you'll probably have similar longevity, though sata drives are moving in the direction of less bang for the buck because there aren't many new ones being developed and the sales volume is going NVMe.
