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lomontman

macrumors newbie
Original poster
Nov 9, 2018
13
0
My wife and I have identical iMacs with the same SSD drives. On her computer a drive "PCI-Express Internal Physical Volume" shows up - it does not appear on my iMac at all. It cannot be unmounted. What is it and how do I make it disappear?
 

SecuritySteve

macrumors demi-god
Jul 6, 2017
912
1,020
California
It sounds to me like perhaps your drives were partitioned or formatted differently. Can you take a screenshot of your disk utility with all devices shown? It should look something like this, after you select the "View" option in the left to show all devices:

Screen Shot 2018-11-09 at 8.13.15 AM.png


Edit: We probably should see the output of both iMacs.
 

SecuritySteve

macrumors demi-god
Jul 6, 2017
912
1,020
California
It looks like there are either two physical drives in one of the computers, or there was some partitioning issue that caused the Macintosh HD to be installed on different partitions. I find it odd that if your iMacs are identical, one of your Macs has 500 GB of storage while the other has 1 TB. Are you sure that you don't have a Fusion drive in one of them, and a full SSD in the other?

You may want to look into the System Information (In utilities) -> PCI or NVMExpress and making sure the hardware listed matches under those two windows.
 

lomontman

macrumors newbie
Original poster
Nov 9, 2018
13
0
Both drives are full SSD. I did indeed forget that they are different capacities. Her iMac was upgraded from one that did have a Fusion drive. So perhaps the transfer process had to proceed this way but I would think the Migration process would be sophisticated enough to not propagate the old drive structure onto the new one.
[doublepost=1541787919][/doublepost]Here are some more screen shots of the drives:

Screen Shot 2018-11-09 at 1.18.39 PM.png
Screen Shot 2018-11-09 at 1.22.11 PM.png
Screen Shot 2018-11-09 at 1.22.46 PM.png
Screen Shot 2018-11-09 at 1.22.52 PM.png
 

SecuritySteve

macrumors demi-god
Jul 6, 2017
912
1,020
California
Yeah there must have been a formatting issue. My bet is the old Fusion drive had 28 GB of space, and when it was migrated a 28 GB partition was created to house that drive's data.

All depends on how you migrated it. There are so many ways to do it, all of which have slightly different results. You might be able to get rid of the partition by reclaiming the space onto the parent drive. It's been a while since I've handled that, but I seem to recall that if you boot the Mac in recovery mode to access Disk Utility at the boot level, it can merge disks.
 

lomontman

macrumors newbie
Original poster
Nov 9, 2018
13
0
That makes sense. I'll do a little research to see if I can merge the drives. Thanks for your help. I do remember I had some trouble with the migration, though I can't remember exactly what the nature of the problem was. So perhaps the weird drive structure is based on that issue.
It's not that big of a deal - it doesn't affect the performance of the computer - just one of those little things that I'd like to clean up.
 

mikehalloran

macrumors 68020
Oct 14, 2018
2,081
611
The Sillie Con Valley
Yeah there must have been a formatting issue. My bet is the old Fusion drive had 28 GB of space, and when it was migrated a 28 GB partition was created to house that drive's data.

All depends on how you migrated it. There are so many ways to do it, all of which have slightly different results. You might be able to get rid of the partition by reclaiming the space onto the parent drive. It's been a while since I've handled that, but I seem to recall that if you boot the Mac in recovery mode to access Disk Utility at the boot level, it can merge disks.
Formatting an APFS drive and creating an HFS+ partition in the process is what happened. I've seen this before—heck, I caused it during testing. That was the easy part.

Consolidate the space on an APFS drive while eliminating the HFS+ partition and retaining all my data... I recall that it took a long time. First, I referenced three "expert" web sites with conflicting instructions and had all three up on my side monitors. It took both Terminal and Disk Utility working together to accomplish it. When it finally worked, I could not recall the exact steps that made it happen.

My other choice was always to wipe the SSD and do a complete Time Machine Restore. Although prepared to do that if I had to, I was spared.

One of my tasks when I replace this 2010 (soon?) is to replicate the above and see if there is a clear set of instructions that works to consolidate the space. If not, I'll write a set of my own.

Since your HFS+ partition is so small, you might want to leave it alone. I wish I could point to a web site and say, This is exactly how you do it. Perhaps someone else can.
 

lomontman

macrumors newbie
Original poster
Nov 9, 2018
13
0
My gut thought was that merging the drives is not going to be simple - I'm not that knowledgable about the intricacies of computers - most of my solutions to problems do come from knowledge posted on the web and if there are multiple experts that disagree about how to solve the problem then I probably won't be able to work it out. I did indeed have the thought that I'd just wipe the drive and restore from a TM backup - the challenge there will be finding enough time when my wife is not using the computer to actually do it. So the current drive status may stay put for a while. Thanks for your suggestion.
 

xagao

macrumors newbie
Jun 20, 2020
1
0
My wife and I have identical iMacs with the same SSD drives. On her computer a drive "PCI-Express Internal Physical Volume" shows up - it does not appear on my iMac at all. It cannot be unmounted. What is it and how do I make it disappear?

I was with the same problem I solved it with these steps


cheers
 

lomontman

macrumors newbie
Original poster
Nov 9, 2018
13
0
Thanks for that suggestion, xagao, but my wife's computer no longer has a fusion drive. So I don't want to re-create a fusion drive. Are you saying that your solution simply merges the two drives and the computer no longer thinks of the merged drive as fusion drive?
 
Last edited:

mikehalloran

macrumors 68020
Oct 14, 2018
2,081
611
The Sillie Con Valley
Thanks for that suggestion, xagao, but my wife's computer no longer has a fusion drive. So I don't want to re-create a fusion drive. Are you saying that your solution simply merges the two drives and the computer no longer thinks of the merged drive as fusion drive?
The only way for the Mac to see both drives as one is to create a Fusion drive. That's not a bad idea, actually, Though the gains are few if your PCIe drive is only 28GB, there might be some including faster boot time. Since you've not told us what iMac(s) you have, further suggestions are blind guessing.

If you let us know the year and version plus your MacOS, there might be better suggestions forthcoming.
 

lomontman

macrumors newbie
Original poster
Nov 9, 2018
13
0
Thanks for your reply Mike. Here's the info:
iMac (Retina 4K, 21.5-inch 2017) running macOS Mojave 10.14.6

As you can see this is an old thread from 2018 and the computer is running fine as is. So the "issue" isn't really a "problem". More a matter of tidy housekeeping.
 

mikehalloran

macrumors 68020
Oct 14, 2018
2,081
611
The Sillie Con Valley
Thanks for your reply Mike. Here's the info:
iMac (Retina 4K, 21.5-inch 2017) running macOS Mojave 10.14.6

As you can see this is an old thread from 2018 and the computer is running fine as is. So the "issue" isn't really a "problem". More a matter of tidy housekeeping.
I kind of figured but thanks for confirming. Re-fusing the two under Mojave will have a few advantages but otherwise, it's not an issue.

If you want to give it a performance upgrade, throw away both drives and replace with a single fast NVMe 3 x4 blade like the 970 EVO and the Simtech adapter — you'll save a couple hundred bucks over the OWC at 2TB. If the overall performance and capacity are fine, leave it alone.
 

lomontman

macrumors newbie
Original poster
Nov 9, 2018
13
0
My wife is happy with the computer as is - not looking for a performance upgrade. Little niggly stuff like this bugs my sensibilities, but she doesn't even know the "issue" exists. I'm going to let it ride. What I'm thinking of right now is how to prevent the partitioning issue from re-occurring when we eventually upgrade the computer. But since we often go 10 years on a computer it's not a pressing problem. Thanks for the suggestions.
 

mikehalloran

macrumors 68020
Oct 14, 2018
2,081
611
The Sillie Con Valley
The issue you describe won't exist when you move to a later, more current model Mac. The Fusion Drive is dead. This doesn't mean you can't screw it up — plenty of armchair experts around to help you with that — but if you leave it as Apple intended and use Migration Assistant when the time comes, you'll be good.
 
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