NVMe FAQ from the developer, JimJ740
Q: Is this a signed driver?
Q: What version of OS X does this driver support?
Q: Where should I install this driver?
A: /Library/Extensions – Note that the owner and group for the entire kext MUST be set to root:wheel
Q: How do I set owner and group?
A: sudo chown –R 0:0 NVMeGeneric.kext
Q: What devices have you tested this with?
A: Intel P3700 series, Samsung SM1715 and SM951 series.
Q: Can I boot from an NVMe drive?
A: No, not until someone writes a standards compliant EFI driver for the Macintosh.
Q: Doesn’t Apple supply NVMe drivers and EFI boot ROMs for their new machines?
A: Apple chose to make their NVMe devices and drivers non-compliant with the NVMe standard. Why they use the NVMe name for a non-compliant device and driver is a mystery.
Q: Can I use this to support an NVMe device in an external ThunderBolt enclosure like the Akitio?
Q: Does this driver support hot-plug for ThunderBolt configurations?
A: Yes, however it does not support hot “un-plug”. If you unplug a ThunderBolt connected NVMe device crashes may occur. Caveat Emptor!
Q: Will NVMe devices speed up my system?
A: Maybe. It depends on your configuration and usage.
Q: What affects performance?
A: Device characteristics, hardware configuration, operating system design, and driver architecture. In particular OS X does not support MSI-X and forces CPU0 to handle all interrupts – although the workloop can distribute some of the load. Also, OS X caches heavily and does not provide a true DIRECT_IO equivalent; the combination of these factors makes many OS X benchmarks very bad at characterizing device performance – particularly so with small I/O and very fast devices.
Q: Is this safe to use?
A: Define safe… NVMe devices are just PCIe cards, and are fully electrically compatible with any system with PCIe slots. Could there be bugs in the software that cause data loss or crashes? Absolutely – but I have not encountered them.
Q: Why does my system report still say: “This computer doesn't contain any NVMExpress devices”?
A: Because system report uses Apple’s non-compliant NVMe kext infrastructure. Look under the PCI devices and you will see your NVMe device and it will indicate that the driver has been installed.
Q: What is nvme-cli?
A: This is a command line utility to issue NVMe management commands – if you don’t know what that means you can safely ignore this utility. This utility lets you define multiple namespaces on your NVMe device, as well as letting you query log pages and SMART data.
Q: Who/what is MinnowStor? What do they make and why did they create this?
A: MinnowStor is a startup that has not come out of “Stealth mode”.
Q: Will an NVMe device cause my Classic Mac Pro to overheat or wear out sooner?
A: I will break my own rule about answering only coherent, intelligent questions. It is amazing that “armchair engineers” think the cMP has poor thermal engineering – it is an extremely well designed unit. There is the assertion that the cooling is poor due to high idle temperatures on the northbridge – this is totally by design! Apple likes quiet machines… so they keep the fans low and allow chips to reach temperatures that, while safe, are markedly higher than cheap PC designs [note: this trend continues with the new iMacs and MacPros]. If this bothers you use SMC and kick the fans up a notch – with the fan speed increased my northbridge idles at 47C – much lower than the so-called “well engineered PCs”. You can overheat your northbridge – if you have broken heatsink clips, failed thermal paste, or have a huge build up of dust inside your machine.
Q: What about all the conflicting information and opinions on the internet?
A: Consider the source. There are no editors or fact checkers on the internet.