Resize Mac Fusion Drive sector by sector copy to fit new SSD.

[SpookyCitrus]

Ok, I'll try to keep this short, I'm working on a friends iMac that is setup with a fusion drive. Recently the mechanical 1TB HDD that was in it failed, it started running very slow with super wonky read tests and it no longer boots into MacOS. I was able to sector by sector copy the failed 1TB HDD to a new 2TB SSD, the problem I'm running into now is that the drive will not boot into the OS due to some sort of corruption, but it is fixable by reinstalling MacOS. However, I cannot because the 2TB drive is only showing up as a 1TB drive due to the sector by sector copy and he has less than 9GB of free space which isn't enough to reinstall the OS, plus due to it being a fusion drive I cannot for the life of me figure out how to resize the partition to fill the full 2TB drive giving me enough space to reinstall MacOS. The data on this drive is very important and is irreplaceable business documents so any help would be much appreciated.

 

TLDR: Is there a way to resize a mac fusion drive partition to fit a bigger drive?

[Kilrah]

Resizing partitions is a pain/sometimes impossible on mac.

 

1 hour ago, SpookyCitrus said:

The data on this drive is very important

So before anything start by connecting the copied drive to another mac and copy anything important to yet another drive.

 

Once that's done, if you boot in recovery mode / from a MacOS installer USB and launch Disk Utility see if it lets you resize the partitions there, but it's likely you'll have to wipe and do a clean install then copy the documents back.

[SpookyCitrus]

9 minutes ago, Kilrah said:

Resizing partitions is a pain/sometimes impossible on mac.

 

So before anything start by connecting the copied drive to another mac and copy anything important to yet another drive.

 

Once that's done, if you boot in recovery mode / from a MacOS installer USB and launch Disk Utility see if it lets you resize the partitions there, but it's likely you'll have to wipe and do a clean install then copy the documents back.

Tried that, since it is a fusion drive when the copy is plugged into another Mac it shows as an un-formatted partition. It only shows up properly in DU on the Mac with the fusion drive cache SSD installed, and even then the partition assistant in DU sees the 2TB as a 1TB drive so it shows zero free space, and thus I cannot resize it. I am currently imaging the OS to another drive through DU to at least have a copy of the data that way, another friend of mine in the field says that I can also restore from that image so I can try that as well. Regardless, I should be able to use DU to move the files to an external as I can see them in DU and should be able to copy the raw files over that way without the OS or applications. I just wanted to see if I can find a way to resize it first so it has enough space to do the reinstall to fix MacOS, but alas I don't think it's going to work with the way fusion drive works on Mac. 

[Kilrah]

2 hours ago, SpookyCitrus said:

I just wanted to see if I can find a way to resize it first so it has enough space to do the reinstall to fix MacOS, but alas I don't think it's going to work with the way fusion drive works on Mac. 

Yup, it's very possible that if both SSD and HDD aren't working correctly the volume is uneditable since it's a merge of the 2. Hence copying anything important first becasue there's quite some risk modifying the original (or copy) will just break everything. 

[SpookyCitrus]

On 12/5/2022 at 5:07 PM, Kilrah said:

Yup, it's very possible that if both SSD and HDD aren't working correctly the volume is uneditable since it's a merge of the 2. Hence copying anything important first becasue there's quite some risk modifying the original (or copy) will just break everything. 

Got it figured out, after doing the Image backup in DU I was able to fresh install Monterey and then use the image backup in migration assistant to move his apps and data over. Only "problems" I ran into were it took 9 hours to do the image from SSD to SSD over USB, and then I had to delete and disable the 24GB Fusion cache drive before installing the new OS onto the new 2TB SSD as it wasn't accessible with the Fusion drive still active.