mac disk utility does not recognize external hdd

I then did a quick search for ways to force Mount HDDs and foun d another SE page with some useful Terminal commands. I unplugged it and tried it on a Windows PC and it worked fine, gave a warning about something being wrong but allowed access and it worked fine. It was shown in the Disk Utilities app but would not Mount (nothing would happen) and First Aid would not work on it (kept returning an error). It suddenly and unexpectedly did not Mount after a reboot. I have a 4TB WD My Passport, ExFAT, being used on MacOS 10.14.6 Just wanted to record my experience for those who follow after. macOS requires the EFI volume to be unmounted or it will complain about not properly ejecting disks. The volume that fails to mount is the primary exFAT volume. I/O size (minimum/optimal): 4096 bytes / 4096 bytes Sector size (logical/physical): 512 bytes / 4096 bytes Notice the GPT PMBR size mismatch – maybe it has some relevance? GPT PMBR size mismatch (4294967294 != 2743150591) will be corrected by w(rite).ĭisk /dev/sdq: 7.3 TiB, 8001562869760 bytes, 15628052480 sectors $ diskutil info disk2s2 | grep 'Block Size' $ diskutil info disk2s1 | grep 'Block Size' MacOS: $ diskutil info disk2 | grep 'Block Size' I don't have the faintest idea where to start on this issue – what could be the problem here? NB: (I tried following these instructions for FUSE for macOS, but I suppose they're not really relevant since exFAT should be supported natively in macOS these days.) Mount: disk2s2: unknown special file or file system.

The drive also shows up in diskutil as disk2s2 but I can't mount it: /dev/disk2 (external, physical):Ģ: Microsoft Basic Data WD My Book 8.0 TB disk2s2 The drive mainly contains a Synology HyperBackup file (.hbk) which makes up almost single-handedly all of those 4.2 TB.Īccording to Synology DiskStation, the main partition is exFAT and I think the EFI partition is vfat: As can be seen in the screenshot below, usage is around 4.2/8 TB. I have run 'First Aid' with no errors.ĭisk Utility incorrectly thinks that the usage is 8/8 TB. The drive shows up in Disk Utility, but mounting does nothing. I am able to mount and read the drive when I connect it to the NAS, but not on macOS Sierra 10.12.6.

I can't recall exactly how it was formatted, but I believe it was done with Synology's DiskStation for my Synology NAS. I have a Western Digital MyBook (25EE) 8TB External Drive.

Mac disk utility does not recognize external hdd