Reformat unmountable flash drive on mac? - Kingston (DTIU3/2GB) 2 GB USB Hard Drive

Every Mac that has an optical drive has an eject key on the keyboard. Pressing the eject key will eject a CD or DVD.

The eject key has this icon on it: ?

You can also right-click on the disk icon, then choose "Eject" from the pop-up menu.

You can also click once on the disk icon, then choose "Eject" from the File menu.

You can also drag the icon to the Trash icon in the dock.

The eject key will only eject CDs and DVDs, but all of the other methods described above will also unmount other media types, like a hard drive or flash drive connected via USB, FireWire, or Thunderbolt.

Before you unplug an external hard drive, you need to unmount it first. If you don't, you can cause all kinds of problems.The term "unmount" basically means to prepare a drive to be unplugged from the Mac. In addition to external hard drives, "thumb drives" a/k/a "jump drives" as well as some cameras need to be unmounted before they are unplugged.When you unmount a drive, Mac OS X checks to see if you have any open files that are stored on that drive. If you do, the drive cannot be unmounted. This is a safety feature because if drive is removed with open files on it, the application that is using those files can become confused and you can lose or corrupt your data.
If you unplug a hard drive that has not been unmounted, Mac OS X will pop up a box with a red Stop icon and a message that you shouldn't have done that. Nice info, but a little late at that point.
I'm not saying that you will lose data every time you unplug a mounted drive, but the danger is there. I recently worked with someone who had his iPhoto Library on an external drive and he never unmounted the drive before unplugging it. It wasn't a problem for a long time but one time he opened iPhoto and all of the photos were missing.
Unmounting a drive is easy. There is an Eject icon to the right of the drive name in the DEVICES section of a Finder window. Just click that icon.
If you have multiple partitions to unmount, you can hold down the Option key when you click the Eject icon to unmount them all at once.
I thought about it and did some looking and I couldn't find anywhere in Mac OS X that states the need to unmount before unplugging, other than the big Stop icon you get after the fact. I don't think it is something you are likely to think of on your own, either. But now you know.

Reformat with camera. iOS / Mac has different file allocation table (structure).

Your drive may be in NTFS file format that is not supported natively by your mac, try looking for NTFS support or reformat your drive to FAT32.

is it formatted in FAT or FAT32? in order to be recognized in mac you have to format in FAT32

If the drive is formatted with NTFS (the format used by recent Windows operating systems), then you won't be able to write to that file system.

What you will need to do is reformat the drive to HFS or FAT32.

If you will be moving the drive between a Windows and a Mac, then you'll have to format with FAT32. If you will only be using the drive on your Mac or other Macs, then format the drive with HFS.
NOTE: unless you copy the existing files off of the drive first, you will lose all data on the drive.
To do this, do the following:

• Copy all existing data off of the Seagate drive to a safe location
• Unmount the Seagate hard drive
• go to your Machintosh HD / Applications / Utilities folder and start "Disk Utilities"
• Select the Seagate drive from the list
• click on the Erase tab
• Select the Format. For HFS choose "Mac OS Extended (journaled)" for FAT32 choose "MS-DOS FAT"
• Type a name for your volume in the Name: field
• Click the "Erase..." button and allow the Disk Utilities program to format the drive
• Once the drive is formatted, you will be able to save files to the disk.

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This is a known issue with mac. If you have a windows based pc, plug the usb there and delete all the files. You will be surprised to see that there are remnant files in there from mac.

I suggest an application called "Disk Warrior" it has always maintained high ratings among us Mac enthusiasts it has a hardware test function built into it and seems to be a little better at verify and repair functions than Disk Utilities which you can try also if you haven't yet. You may also consider trying a different firewire cable if you have one handy. Other than that a reformat should have put the disk back into an original state however the disk could have been damaged by not un-mounting it in rare mac cases. If you have the time you can also reformat the disk again although I would try the first two options first.

what are the tips of hard disk drive troubleshooting

Right click on the item in the taskbar and select eject or unmount. Each one is diff but that is a common practice.