Since my upgrade to High Sierra, can't restart from drive cloned onto RAID - JBOD

[Freeþinker]

I only recently made the jump to going from Sierra to High Sierra. There was no trouble in upgrading the auxiliary internal SSD that I'd already been using with Sierra before upgrading. My main (also internal SSD) drive, though, has been a (Disk Utility-created) software RAID with a concatenated scheme. It was an affordable way to combine a 2TB SSD with a 1TB SSD. (A RAID-0 would not have given me the needed extra capacity.) I followed the advice of many (using a Time Machine back up) to 1.) erase the drives of the old RAID and create a new RAID with the new Disk Utility 2.) then install High Sierra onto an entirely different high-capacity (cheap rotational) drive using the migration from the Time Machine 3.) Clone the contents of the entirely different drive onto the recently created RAID (I did this with Drive Genius) 4.) Restart in Safe Boot mode and choose the new RAID

I've had no success with getting the new RAID to work as a Start volume, despite having successfully started up with the third drive prior to cloning its contents onto the new RAID scheme. I have access to all the contents, but I can't restart with it. I don't want to be stuck with using the slow rotational drive or go back to Sierra and the old RAID. How can I get the new RAID to work as a start drive--with the concatenated scheme?

Model Name: Mac Pro

Model Identifier: MacPro5,1 [after hack firmware install that functioned under Sierra and then Apple's recent firmware upgrade]

Processor Name: Quad-Core Intel Xeon

Processor Speed: 2.66 GHz

 

[marzer]

I only recently made the jump to going from Sierra to High Sierra. There was no trouble in upgrading the auxiliary internal SSD that I'd already been using with Sierra before upgrading. My main (also internal SSD) drive, though, has been a (Disk Utility-created) software RAID with a concatenated scheme. It was an affordable way to combine a 2TB SSD with a 1TB SSD. (A RAID-0 would not have given me the needed extra capacity.) I followed the advice of many (using a Time Machine back up) to 1.) erase the drives of the old RAID and create a new RAID with the new Disk Utility 2.) then install High Sierra onto an entirely different high-capacity (cheap rotational) drive using the migration from the Time Machine 3.) Clone the contents of the entirely different drive onto the recently created RAID (I did this with Drive Genius) 4.) Restart in Safe Boot mode and choose the new RAID

I've had no success with getting the new RAID to work as a Start volume, despite having successfully started up with the third drive prior to cloning its contents onto the new RAID scheme. I have access to all the contents, but I can't restart with it. I don't want to be stuck with using the slow rotational drive or go back to Sierra and the old RAID. How can I get the new RAID to work as a start drive--with the concatenated scheme?

Model Name: Mac Pro

Model Identifier: MacPro5,1 [after hack firmware install that functioned under Sierra and then Apple's recent firmware upgrade]

Processor Name: Quad-Core Intel Xeon

Processor Speed: 2.66 GHz

I haven't toyed with a boot RAID under High Sierra yet, but I've read multiple accounts of folks who found they could no longer boot from RAID under HS. Although concatenating drives are my least favorite for combining drives into a single volume, I understand your reasoning to maximize the storage.

Since you are not getting any speed advantage, the obvious solution would be to create a fusion drive with the two SSDs. You get the benefit a of single mass volume just like concatenation and the drive is inherently recognized by macOS for booting. And if one drive is faster than the other, you might see minor speed improvements through the buffering scheme during access times to the slower unit.

 

[Freeþinker]

I haven't toyed with a boot RAID under High Sierra yet, but I've read multiple accounts of folks who found they could no longer boot from RAID under HS. Although concatenating drives are my least favorite for combining drives into a single volume, I understand your reasoning to maximize the storage.

Since you are not getting any speed advantage, the obvious solution would be to create a fusion drive with the two SSDs. You get the benefit a of single mass volume just like concatenation and the drive is inherently recognized by macOS for booting. And if one drive is faster than the other, you might see minor speed improvements through the buffering scheme during access times to the slower unit.

I'm grateful for your suggestion. I'm going to research creating a fusion drive with two SSDs of unequal capacity. I hadn't thought of that, and it might be a very worthwhile option. Thank you, Marzer!

 

[marzer]

I'm grateful for your suggestion. I'm going to research creating a fusion drive with two SSDs of unequal capacity. I hadn't thought of that, and it might be a very worthwhile option. Thank you, Marzer!

You're welcome. Here's a good source. And remember to list the fastest drive first to give it priority for buffering when creating the CoreStorage volume.