General discussion • What's with the M.2/NVMe obsession?

Full disclosure: I have a couple of Pi5 booting from NVMe. Beacuse A. it's possible, and B. I wanted higher volume local storage that didn't take up a USB port. Though I'm considering reverting one back to SD as I don't need either the capacity nor the performance boost. I've PI5 and CM4 based systems that boot of SD card too.

Can someone please enlighten me as to why folks are obsessing over having M.2 and NVMe on Pi, some to the point of its lack being a deal breaker on the new 500.

Yeah, NVMe is:

• Faster than SD
• A slightly better match to the physical dimensions of the Pi than 2.5" drives but that depends on the selected NVMe HAT/HATlike device.
• Quieter than HDD
• Faster small, random, uncached IO.
• Less cable spaghetti
• higher capacity than SD (but that depends on what you buy)
• Long term reliability (but that is very dependent on use case)
• Doesn't take up a USB port

But it also has a number of downsides that, for me, mostly out weigh the advantages:

• Requires additional hardware
• More expensive (see above)
• Needs more power (yes, really)
• Fragile ribbon connector
• Adding more than one needs additional hardware and splits bandwidth.
• The Pi5 seems much more picky about NVMe drives than it does SD cards.
• More hassle than SD/USB for swapping between OS as you can't just unplug one and plug in another. Yeah, I know it's possible but more steps and tools are involved. I also know there are ways to muck around with boot order and GPIO based conditional filters but I suspect most folks obsessed with NVMe won't have a clue about those.
• No more bandwidth over PCIe than there is over a USB 3 port (unless running at the uncertified gen3, which may or may not work for you)
• Sustained transfers (like streaming video) won't be any faster than from an HDD or SSD drive. Any decent SATA III device can saturate the USB 3 interface just as NVMe can saturate the PCIe one.
• Network applications (like a DIY NAS) won't really benefit as the performance limit will be the network. And while I'm on the subject of DIY NAS, the huge additional expense of NVMe vs spinning rust once you go over ~1TB.
• Then there's the big one: you'll never see the full rated performance of the vast majority of NVMe drives. Most are designed for 4 v4 PCIe lanes. There's a single v2 lane available.

But yeah, there are use cases but if it's a deal breaker my feeling is that you probably should be using something with more grunt that a PI.

So why the common obsession? Because it's there?

Statistics: Posted by thagrol — Tue Dec 31, 2024 11:14 pm

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