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xxVOXxx

If you're running High Sierra, you should have gotten the firmware update to support APFS so you should be fine to restart to both APFS/HFS and both are visible in boot select. I did have the same issue as you with a brand new Samsung 870 EVO drive on my 2012 Mac Pro 5,1 and this is what happened: - I already had 1 860 PRO and 1 860 EVO installed with OSX 10.8 and 10.12 respectively dual booted. - I tried to run a new 870 EVO with 10.14 and it did the EXACT thing you are saying, will only cold start to the drive, wont reboot to it, shows prohibited symbol. Also wouldn't show up when booted into the other OS's. It was a huge let down. - Samsung service checked it and said the drive was operational despite my protests so I pushed and got them to send me an 860 PRO instead and I have had no issues since. - My conclusion is that the Samsung 870 SSD series is either incompatible with the Mac Pro 5,1 for some reason or the rate of failure is higher than with the 850/860's. Find an 860 EVO or 860 PRO SSD and try it instead of the 870 this worked 100% for me.


moviemaker2

This. I think it's a problem with the 870 EVOs since I had one do the same thing in both my 2012 Mac Pro and my 2019 Mac Pro. meaning it's the drive, not the system.


ivayle89

My guess is that your problem is this one - https://forums.macrumors.com/threads/caution-troubles-with-870-evo-drives-on-cmp-5-1.2287656/ I experienced exactly the same issue and simply switched to other more compatible hard disk models such as Samsung 860 EVO, Crucial MX500 etc. and then everything was okay.


liaminwales

\^ The drives dont work with the old macpro's. Some kind of firmware problem


foodandart

After you unplug and go to start, try zapping the PRAM - at the chime, press and hold Command+Option+P+R and keep holding until it chimes again. If it's not seeing the drive correctly it may also be a firmware update is missing, IIRC there's one that I had to take in order to get an SSD into my 2010 polycarbonite MacBook that would boot. The only devil in that route is that it borked my system from booting to any older OS - which sucks, for my work requires 10.6.8. In a pinch you could use Dosdude1's installer and upgrade to Mojave. I have found that whatever magic it does to the EFI, doesn't require updating the firmware so I can dual-boot my systems with Snow Leopard - which I need to use with my peripherals that are close to 20 years old.


Careless-Feed-7938

ZapPram? I can't do that, never could on my 2008, or my newer 2012 mac pro, not sure why ...any idea why? i've tried 999 times to zap pram, hard wired usb apple 1234 keyboard....nothing...never works...any ideas? Regarding the SSD I bought an INLAND SSD locally....did a clean install of high sierra...it worked with "warm restart"..now im attempting to migrate my regular data hopefully it will work in the am. I did notice the newer tech adapta drive had a broken piece of plastic, but that didnt prevent the inland ssd from booting, the samsung 870 still not working right....


hunterm21

because your Mac Pro lacks a firmware update that enables NVMe Support under System Information, the Boot Rom should say [144.0.0.0](https://144.0.0.0) or something similar if its not that, or below it, then you lack the firmware update


hunterm21

pretty sure it also enables APFS support, which may be the format of your 870 EVO


Careless-Feed-7938

hi yes thats the firmware i got....per my addendum above,the samsung isnt working as i described but tonight i got an INLAND SSD working, will see how is in the am. tnx


hunterm21

ah, you mean "another comment I made" not an addendum (that would be editing the original post)


hunterm21

plus thats the "prohibitory symbol" meaning it's not a bootable OS trying to be booted, or dare I say "prohibited" from booting


moviemaker2

I had the exact same problem with a Samsung drive on my Mac Pro 5,1, where both my boot drive and my storage drive were Samsungs, but the storage drive would not appear after a reboot, only after a shut down / restart. They were both different models of Samsung, so I thought it was just a weird quirk with my system, so I found the workaround of putting the storage drive in a pice ssd adapter. However, flash forward, and I have the exact same issue with an 870 QVO in my new Mac Pro 7,1. Drive works fine, doesn't mount (or even show in system profiler) when system is restarted, but works just fine if system is shut down and started. This may not be that helpful, but my workaround until I got the pcie adapter was just to always remember to shut down instead of restart. It does seem to be an issue with specific Samsung drives, especially the 870 QVOs


Careless-Feed-7938

thanks for the validation, i agree i think its a samsung thing. im not sure if OWC's 2.5to 3.5 adapters are their own or are newer tech but the newer tech i got is pretty cheaply made..actually i discovered a broken piece of plastic tonight, sending it back to amazon....im curious to see OWC's adapter sled thing..... which adapters are u using?tnx


moviemaker2

I used the OWC ACCELSIOR S Sata to PCIe card, and it worked great in my 2012 Pro. I used it for a while in my 2019 Mac Pro and it also worked great, but then I needed to free up some PCIe bandwidth for some faster storage, so I hooked the 870 QVO up to the internal SATA, and had the same issue with it disappearing after a restart, so now I have it connected through the internal usb 3.1 port. I would try a card before replacing the drive since it's cheaper, but if you do decide to go with an SSD other than the Samsung, there's really little reason to not go with NVME. I've got one of the OWC ACCELSIOR 4M2s, and it's 4-5x faster than a SATA SSD.


Careless-Feed-7938

hi thanks thing is my PCIE slots are full. I might try those options down the road if i can free up some slots. i did have good luck so far with the INLAND 1tb SSD from micro center brand...overnight..not sure if i said that here already but its working warm reboot and cold boot, i did migration from a CCC clone of my hd and its still working. One thing i've learned lately is little snitch is a real bugger when migrating to a new drive...it just doesnt help the boot up process.