MacBook Pro will not mount ExFAT formatted external drive

JD1701 wrote:

Uh-oh...now my ignorance is making an appearance! :) My situation is this; I have been storing my image files on (now 7) WD external hard drives formatted to mount to my MacBook Pro, where my old PS CS editing software is located. I have an LG Gram that I travel with and store my image files on. I now want to have my external drives mountable to the PC and Mac for storage and accessibility requirements.

I thought of something else.

If you're traveling with one notebook, while leaving the other at home, with the drives that hold the pictures, file sharing would raise these issues:

The notebook that stays at home would need to remain powered on, and you would need to make it accessible from the Internet – not just from your local network. The notebook that is traveling with you would be pulling in files over the Internet. Depending on the number and size of files you were working with, and the speed of your Internet connection (on the go and at home), that might not be the fastest thing …

JD1701 wrote:

I have a 2009 MacBook Pro. I bought a new WD Essentials portable HD. It won't mount on the MacBook. Will it not because I cannot update my OS to anything more current than the 10.7.5 I have on there now, and therefore the drivers I need are not the most current for this new HD? My older WD HD's mount with no problem.

Did you erase, reformat and initialize that new WD as new...using the Disk Utility.app

ref: Erase a volume using Disk Utility on Mac - Apple Support

this will remove any proprietary software that comes preinstalled on it.

The last update to OS X 10.7.5 was 2012

Yes and No. ExFAT has certain naming conventions, is not bootable on Mac OS, and will not yield a true clone when backing up via clone or even a recoverable Time Machine backup. If you want to loosely backup documents that work on both platforms, then yes, you can do that.

File sharing PCs and Macs is a far better way to avoid this problem.

Share Mac files with Windows users - Apple Support

Mojave and High Sierra directions most clonely approximately Lion's setup. But you will not be able to use APFS formatting on Lion at all. HFS Extended GUID is needed for Lion.

JD1701 wrote:

Will it not because I cannot update my OS to anything more current than the 10.7.5

A 2009 model can run up to macOS 10.11 El Capitan.

my friend did all the moving of data and reformatting on his Windows 10 machine. Would it work for me if I did this on the 2009 MacBook Pro? Do I have to format it exFAT using my MacBook Pro for it to be mountable on it?

exFat can be tricky. It is usually best to use Disk Utility to erase the drive as exFAT instead of using Windows to format it with exFAT. macOS is more limited in its exFAT implementation than Windows. Windows may format the drive using a File Allocation size that is not compatible with macOS. It is possible the exFAT implementation with macOS 10.7.5 is even more limited than more recent versions of macOS.

Plus, more than likely your friend only reformatted the partition and did not delete all partitions to start over from scratch to create a new partition table. The drive manufacturer's will sometimes do strange things with the partition table and may even sneak some hidden stuff onto hidden areas of the drive that may affect some operating systems differently. On macOS you would want to use Disk Utility to erase the whole physical drive as described in the following Apple article:

Erase and reformat a storage device in Disk Utility on Mac - Apple Support

Actually if you want to do this on the old macOS 10.7.5, you would need to instead partition & format the drive using Disk Utility to have it recreate the partition table (requires the partition tab). With macOS 10.11 you would just use the "Erase" tab like with later versions of macOS.

It could also be a compatibility issue with the newer style drive and macOS 10.7.5. The older versions of macOS such as 10.7.5 assumed a block size of 512 bytes while newer drives use a 4k block size. Some drives will show the OS a 512 byte block size to older systems, but some newer drives no longer do that and only show a 4k block size. I forget when this would have changed in macOS, but macOS 10.11 I believe will likely be able to deal with a drive that only reports 4k blocks.

The Windows machine will not maintain the bootability of any drives it manages.

The WD software likely is not compatible with your Mac. If you reformat it with Disk Utility on your Mac after backing up to another drive, you will be better off.

You might want to get a second drive to copy any info you need on it before reformatting anything.

File sharing means having one computer serve up its disks to another computer over the network.

The computer offering the files acts as a sort of NAS (network-attached storage unit), and the computer that's accessing them remotely sees them as being stored on a NAS.

This is generally slower than accessing a directly-connected drive, and sometimes applications will not permit certain files to be stored on network drives or will not work well if you store them there. E.g. Lightroom Classic would likely be very unhappy if you tried to store its catalog files on a network drive. If you kept the catalog on local drive(s) and the images on network drives, that might work – though I don't know how easy it would be to move a Lightroom Classic catalog between the two platforms given different filesystem naming conventions.