4GB FLashdrive Format Terminal Problem/ Question.

Your screenshot and output from the terminal doesn't show any flash drive.

It just shows your 500GB Hard Drive (disk0), which as normal shows a 200MB hidden partition (disk0s1) which is normally for the EFI (created as part of the GUID partition scheme), and the OS partition (disk0s2).

 

I would leave disk0s1 and anything else related to disk0 alone as thats your hard drive not the memory stick.

I notice you have VirtualBox, you will want to make sure it hasn't taken control of your usb devices, specifically the memory stick. So make sure it's closed. Then try diskutil list again and see if it lists a second disk. If it lists it it should also appear in Disk Utility and you should be able to format it.

I've had some odd occasions where I've needed to wipe the drive completely and then reformat, for that I've used something like "dd if=/dev/zero of=/dev/disk1", but for that the drive must show up in the diskutil list.

 

What type of flash drive? Where did you buy it?

http://figpond.com/

 

That's an excellent point. I once bought a 4 GB drive on ebay only to find it was a 256 MB drive "formatted" to look like it was 4GB. As soon as I copied 257 MB of files to the thing, it started having errors. The HK seller wanted me to pay to ship the worthless thing back. I refused to pay return shipping for fraud. I filed a claim and got my money back. In my case, the reason my usb stick turned into a 200 MB drive wasn't Windows or any OS, it was that when formatted properly it was really only a 256 MB usb stick.

@Esutick: As for using terminal to manage drives, I say find better method. If you don't (yet) realize how dangerous it is to do something to disk0, especially when it clearly shows it is 500 GB, not 4 GB, you really should avoid using the bash shell to attempt to manage a usb stick! If you don't want to be faced with a grey screen with a question mark saying "no operating system", stick with disk utility and avoid touching anything named Macintosh HD and anything Macintosh HD is indented below. In your screen shot, that would mean keep your hands off "500.11 GB WDC WD500" and everything indented beneath it as that is your operating system and user files and things can go terribly wrong very quickly if you start making changes to those items.

When I get a new memory stick or external HDD, the first thing I do is let Disk Utility format it HFS+. If it's big enough (8GB+) to use for an install disk, I make it GUID partition scheme HFS+. FAT32 is something I avoid unless I specifically want to share files across OSX and Linux or Windows.

In the screen shots you posted, your USB stick is not mounted. It should automount when you plug it in. If not, try looking for it in Disk Utility.

 

How many ways can I say leave that 200MB thing alone. It isn't something you should be tempted to mess with...

Code:

/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *500.1 GB   disk0
   1:                        EFI                         209.7 MB   disk0s1
   2:                  Apple_HFS r0k Macintosh HD            499.2 GB   disk0s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3
/dev/disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     Apple_partition_scheme                        *1.0 TB     disk1
   1:        Apple_partition_map                         32.3 KB    disk1s1
   2:                  Apple_HFS ExternalFWDrive                   1.0 TB     disk1s3
/dev/disk3
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     Apple_partition_scheme                        *3.4 MB     disk3
   1:        Apple_partition_map                         32.3 KB    disk3s1
   2:                  Apple_HFS Install Balsamiq Moc... 3.4 MB     disk3s2
/dev/disk4
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     Apple_partition_scheme                        *37.1 MB    disk4
   1:        Apple_partition_map                         32.3 KB    disk4s1
   2:                  Apple_HFS YamiPod (MacOS X)       37.1 MB    disk4s2

In this case my boot drive is disk0. Disk0 is almost always the boot drive. To further muddy the waters, any disk images I happen to have mounted show up on the list even though they are just dmg files sitting in my downloads folder.

Your memory stick definitely should NOT be showing up as disk 0. On my Mountain Lion test machine, I boot from an external drive so things are a bit more interesting...

Code:

/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *320.1 GB   disk0
   1:                        EFI                         209.7 MB   disk0s1
   2:                  Apple_HFS r0k Macintosh HD            208.2 GB   disk0s2
   3:                  Apple_HFS r0k Macintosh HD 2          111.4 GB   disk0s3
/dev/disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *160.0 GB   disk1
   1:                        EFI                         209.7 MB   disk1s1
   2:                  Apple_HFS r0k Old Macintosh HD    159.2 GB   disk1s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk1s3
/dev/disk2
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *8.0 GB     disk2
   1:                        EFI                         209.7 MB   disk2s1
   2:                  Apple_HFS Mac OS X Install ESD    7.7 GB     disk2s2

Now my boot drive is disk1

In this case, you see my usb stick shows up as disk2. Never disk 0 anything and I should add a USB stick can never show up as diskX where X is my boot disk.

Notice how I have a 200ish MB disk0s1? In fact I have them on every disk, even my 8GB ML install usb stick. I'm not even mildly tempted to mess with any of them!

Does this mean your stick is bad? I don't know. It's only 4 GB. For about 10 bucks you can get a new 8 GB stick and move on.

BTW, I also notice that sometimes if I format a usb stick on my Mac in "FAT" format, Windows machines can't see it. For this reason, if I buy a usb stick and I intend to share with Windows, I don't format it on OSX, I simply write to it from my Mac and if it ever needs formatting, I let Windows do that.