Would you try this:
1. Open Disk Utility in your Utilities folder.
2. After DU loads select your hard drive (this is the entry with the mfgr.'s ID and size) from the left side list. Click on the Partition tab in the DU main window.
3. Under the Volume Scheme heading set the number of partitions from the drop down menu to one. Set the format type to Mac OS Extended (Journaled.) Click on the Options button, set the partition scheme to GUID then click on the OK button. Click on the Partition button and wait until the process has completed.
4. Select the volume you just created (this is the sub-entry under the drive entry) from the left side list. Click on the Erase tab in the DU main window.
5. Set the format type to Mac OS Extended (Journaled.) Click on the Options button, check the button for Zero Data and click on OK to return to the Erase window.
6. Click on the Erase button. The format process can take up to several hours depending upon the drive size.
I don't know what you are looking at to determine space available. You need to do that by selecting the device's Desktop icon then press COMMAND-I to open the Get Info window. The capacity and available space will be displayed in the Get Info window. A portion of the device will be allocated for the RDB and directory, so some space will be shown as in use.
Apart from the full erase, those are the steps I am using. A full erase is very time consuming and should not be needed in order to get USB flash drives to format.
After performing the partition procedure, DU shows the graphic of the drive, and part is blue, and part is white. I believe the blue part is the portion that was not (for whatever reason) part of the partition created. It also says to the right of that, the total size of the drive and some amount of GB as "available". I presume that amount it shows as available is the portion that was not used in the partition. When I format a 4GB USB flash drive, it all shows as part of the 1 partition, and says nothing about any amount available (which is how it should be).
Since this is happening on 4 different 8-16GB flash drives, I doubt it's a flash drive problem, and since my Mac mini server did the same thing on one of the 8GB flash drives, it doesn't look likes it's just my Macbook Pro!
You are correct, but if the device had a Windows partition and format, then the zero data option is recommended but no necessary.
The blue area you see in the partition rectangle doesn't mean a thing. I believe OS X displays that as the space the OS would require for installation. On 8 GB devices it's mostly blue. But that has nothing to do with available space. Use Get Info for that or look in DU's status area after you select the volume (not the drive entry.)
The blue area will not show up on devices smaller than 8 GBs because they are not large enough to install OS X.
If the blue area is meaningless, then I was led astray with that graphic. The fact that DU was showing 8.03GB total capacity, then, to the right of the partition blue/white box, it says "size: 7.69GB, 2.29GB available", it sure looked to me that it was not using all 8GB for the partition.
I will attempt to use the flash drive, as it is formatted, then and see if there is a capacity problem.
Thanks for your help on this!
Bue area is very IMPORTANT. Every time I use to erase the ''current" partition and create a new one (just one) the blue area is getting bigger ( only when you need to use the GPT ) . When you go and do a Get Info the available space is getting lower and lower ...
I am searching this , if I manage to find out information about it I will comment here again.