MacOS – How to Get Expanded Synology Raid to be Recognized in Mac OS


I recently purchased a DS517 to expand my DS1817+ Raid. I went through all the steps on the Synology side to increase the volume size. However, my Mac OS computer is still showing the old size of 53.7 TB instead of the new size of 92.8 TB.

When I try to use Disk Utility and go through the Partition tab. I can select the "Free Space" and click the "-" sign, and it shows the projected new space of 92.8 TB. When I click "Apply" it gives me the error of:

"The new size must be different than the existing size."

In Terminal, when I run "diskutil list" I can see the new size, but the container it's in is the old size. It shows –

/dev/disk4 (external):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                         92.8 TB    disk4
   1:                        EFI EFI                     209.7 MB   disk4s1
   2:                 Apple_APFS Container disk5         53.7 TB    disk4s2

/dev/disk5 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +53.7 TB    disk5
                                 Physical Store disk4s2
   1:                APFS Volume CC-SYN1                 52.6 TB    disk5s1

I've found commands such as diskutil apfs resizeContainer disk4s2 0 that supposedly are supposed to fix it, but it gives me the error of:

Error: -69743: The new size must be different than the existing size

I don't have a spare 54 TB raid sitting somewhere to where I can just format and start over, so I'm hoping there's a way to get the container to show the new size. It's obviously there, but after searching Google for hours and seeing mostly the same "solutions" without it working, I'm not sure what else to do/try.

Best Answer

I figured this out a few days after posting my question, and figured I should followup for anyone else experiencing a similar problem. I came across gdisk and used the following instructions in Terminal to fix the issue:

* Type "sudo gdisk /dev/sdc" (or whatever the appropriate device filename is)
* Type "x" to enter experts' mode
* Type "e" to relocate the backup data
* Type "w" to save your changes.