SD Card Formatting on a MAC

[andyclift]

I spent all yesterday trying to transfer music from my iMAC to an 8 GByte SD card for use in my Zumo satnav. Whatever I did, the satnav could not find any music. Tried a 1 GByte card and that worked perfectly.

Garmin help confirmed that an 8 GByte card should work and that the folder structure was not a problem but apart from that was beaten but I found the problem last night. Use Disc Utility to format the 1 GByte card and it shows as a FAT device with a FAT partition. Use the same method on the 8 GByte card and it shows as a Mac OS Extended device with a FAT partition - although I select the device and choose FAT.

To overcome the problem I put the 8 GByte card in my Digital camera, formatted it and then put it in the iMAC to copy the music. Everything worked OK. Checking this card with Disk Utility shows a FAT device with a FAT partition - the iMAC could read it but can't make it.

Now to the obvious question. How do I make a proper FAT formatted card in the iMAC?

 

[AshR1]

1. Open Disk Utility
2. Select the SD Card device (upper icon), not the SD Card volume (lower icon)
3. Select Erase at the top of the window
4. Select Volume Format: MS-DOS (FAT)
5. Enter a new name for the card if required
6. Click Erase

 

[andyclift]

Yup, thats EXACTLY what I do. On a 1 GByte card it works but on the 8 GByte cards it always results in a Mac Extended Device with a FAT Partition.

 

[AshR1]

I think you are just looking at the drop down list which following the erase reverts to it's default choice. If you now select the partition that has just been created you will see in the info that it is FAT32.

 

[andyclift]

Thanks or the suggestion but no that is not what I am looking at. The PARTITION always formats properly to FAT but it is the device reverting to Mac OS Extended after formatting which causes the problem.

For anyone else with the problem the answer was provided by a person on a Mac forum.

The answer is that the DEVICE (not the PARTITION) must be formatted to FAT (as I was doing) and the Partition Map Scheme must be set to Master Boot Record (MBR)(which I was not doing). If this is not changed manually in the options for the DEVICE before formatting the result is the device reverts to Mac Extended and the Partition to FAT. This is what causes the problem with some Windows devices.

Tried it and it works perfectly and the info for both the device and partition show FAT and MBR as does a card formatted on a camera or PC. If the Partition Scheme is not manually changed the sd info shows a FAT partition plus a Mac Extended Device with a GUID scheme. This is what causes problems with some kit such as my satnav