Chosen Solution
I know this is an old thread, but I would like to hear more from Dan on the Limits, and the “Sizable Chance” he speaks of. What EXACTLY have you seen as issues? Mainly the “Garbage collection” and “Protocols” that Apple runs that would not be supported?; Over-filling any SSD, under any circumstances [including phones] is a source of early failure [I like to leave mine around 1/3 empty]. SO hard to mix and match configurations to get the MOST, without breaking something, or “over-buying and not getting the benefit. I too have a 2019 imac-i9 and am currently booting from an external PCIe 3.0-NVMe-M2-4TB. IF I can’t achieve anywhere near the speeds I am seeing going internal, I won’t waste my time/$. It APPEARS that the 2019 iMAC does support the PCIE 3.0 NVMe-NOT M2? [IF I am reading correctly]; and not the 4.0. . .so I won’t be able to get at least the same speed going Internal? Then perhaps size limitation? I cannot find as a “Matter of Fact” how Large can I go [8TB]?
@mandm_0 - That’s a lot of Q’s! Apple uses a hybrid design using the PCIe lanes and NVMe protocol for the data storage. But the way any SSD does wear leveling and housekeeping (garbage collection) chores are not set in stone! Each vendor does their own thing within the SSD’s micro controller and firmware. This is the bugaboo! As Apple did their own thing and as they also do the rest of the system hardware and OS they did some funky stuff! The systems firmware has also changed so what they did day one is a bit different today and the given series also gets into this. All I can tell you is I’ve pulled out a lot of M.2 drives and their adapters out of many systems! These are mostly pros and advanced amateurs in music, photo and video work. So… what I recommend is sticking with the Apple or OWC drives for the blade drives which you can get upto 2TB. The way you use your drives has a big bearing on the systems performance. I recommend using the blade drive as your boot drive and hosting your apps. Don’t load it up with junk stuff lean and mean! Leaving at least 1/3 of the drive unused! The more the better if you work on large projects so the OS can cache and if needed use the free space for Virtual RAM if your Physical RAM is not enough. Having more also allows some apps to use it for scratch space. Now getting into the external ports your system only offers two Thunderbolt3 (USB-C) ports, so what you plug in for a drive becomes tricky! As an Apple based TB3 drive offers better throughput than a generic PC USB-C drive! But even that is not using the full ability of the I/O channel! This is where RAID setups make a sizable difference! So… where does that leave us? Use the internal blade drive for your OS and Apps leaving enough free space for Caching Virtual RAM and if you use apps which use scratch space, and consider your workflows needs. I would use the Internal SATA port to hold my media and static art. And then use a RAID set for my active work (which is what I do) The version of PCIe is 3.0 per Apple.
Just use a M.2 SSD and a adapter than you have full 3.0 Speed. Faster than the $@$* OWC SSD for internal use
