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OS X - Operating System General OS operation information and support

Disk Utility and removable flash drive (PMP)


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StreetHama

 
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I've some how partitioned the drive of an 8GB portable media player so that the bulk of the drive is now completely invisible to any computer, Mac or PC. I've tried all manner of partition find & restore software with no joy at all. The Ainol P810 player itself is working just fine, it can see and play all the files and both partitions. The 'missing' partition is 7GB and the other part is 200MB which is all that shows up as available when the disk is mounted.

What caused this is, when I first got the device I loaded a few movies (on work Mac) which was all fine, disk shows up in finder, drag n drop... Later when I went to put some different movies on I dragged the old ones to a folder (on home Mac) but noticed that did not free up the space on the disk so I did what I usually do with my thumb drives, open disk utility erased the disk and carried on with all the free space available and put some other movies on. That worked fine - I noticed no differences at all.

I'd had the unit stashed in the garage as it was a gift for my daughters birthday. I got it out a couple of days ago to load on some more movies. Thats when I noticed no files showed up in the drive that was mounted (200MB) and could not find the files that are still on the disk.

As I said I've checked it on a PC with Disk Manager, Easeus, something called FindandMount (and Disk Utility) and a few other free things but nothing will see the 7GB partition.

Disk Utility has done something to it. What could it be? I think I kept it on the default setting when I erased it but most likely went for MS-DOS (FAT) format.

Sorry for the length of this post I want to give as much info as possible in the hope that some one can help me out!
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chscag

 
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Common problem when using Disk Utility to either format or partition a flash drive. Long story involved. Short story: Don't use Disk Utility unless you know how to format the flash drive without creating an EFI 200 MB partition.

Anyway, here's how to resolve it: You'll need a working PC with Windows to do it or a dual boot Mac with Windows. (Can not use OS X)

Follow the instructions given at this LINK carefully. Read them first and make sure you understand what's being done before doing it.

Regards.
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StreetHama

 
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Thanks for your post. I came in to work today with much hope because it sounds like you have figured out exactly what I've done.

Unfortunately when I list disk I only get:

Disk 0 Online 932 GB 129MB(free) this is my main hard drive
Disk 3 Online 298 GB 254MB(free) this is my external USB back-up drive

I realised that it's good that it is seeing the USB drive as it was connected on start up. So I connected a thumb drive & my problem dive and restarted. Same result - cant see the flash drives at all but they are both shown in my computer.

Any ideas? Your time is much appreciated!

... I tried > list volume and that got the 200MB P810 to show up and another one shwoing as 0MB both of them dissappear when I eject it so they are both on the same drive
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Quote:
... I tried > list volume and that got the 200MB P810 to show up and another one shwoing as 0MB both of them dissappear when I eject it so they are both on the same drive
Try this: Remove all external drives and only attach the portable media drive. If you at least are able to "see" the 200 MB partition you should be able to use the procedure I gave you to erase the drive and then format it again correctly.

If the drive shows up from My Computer that means it can be seen by the system. Even if it doesn't read out from the Command Prompt, go ahead and give the command to erase it just like it's there. Don't worry about accidentally erasing your internal drive as that can not happen as long as it's mounted and Windows is running.

Let us know.

Regards.
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StreetHama

 
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Gee that makes me feel nervous! I did as you said and have disconnected everything but the drive I want to work on. list disk now only shows Disk 0 Online 932 GB as before. So as there is only 1 disk showing do I select that and then clean?

Ok did that would not clean it phew! It does not want to clean while no disk is selected.

It seems every thing I try has the same problem. It just cannot see the disk. DISKPART can see the volume but it wont let me clean that.
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Quote:
Gee that makes me feel nervous! I did as you said and have disconnected everything but the drive I want to work on. list disk now only shows Disk 0 Online 932 GB as before. So as there is only 1 disk showing do I select that and then clean?

Ok did that would not clean it phew! It does not want to clean while no disk is selected.
You should have given the command to clean Disk 1 not 0 even though Disk 1 does not show up. Try that. As I stated, there's no danger for Disk 0 since it's mounted and you're using it to give the command from.

However, it's a real mystery why that drive won't show up from Disk Manager but does show up in My Computer. When you see the drive in My Computer what format does it show for the partition that you can see? (200 MB)

Regards.
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StreetHama

 
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It does show up in disk manager & my computer but not in DISKPART. I tried that before and again. It says "The disk you specified is not valid. There is no disk selected."

I tried it with disks 1 through 10 and same thing... Me and Disk Utility have cocked this up real good!
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I'm going to have to try to do some more research on this one. I'm mystified why that disk shows up in My Computer and Disk Manager but Diskpart doesn't know it's there. Getting late.

Regards.
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I may not be following the thread here well and could be misunderstanding something along the way, but I've formatted flash drives using Disk Utility a few times and have never had a problem with lost space. In fact, I have one in particular with OS X installed to it along with various utilities in the event of a failure with my internal drive.

I suggest looking over this tutorial linked below to see if any of the steps help out. In particular, make sure there is only 1 partition. Also, with respect to the directions involving the GUID, be sure you select the first or second option, as it applies to you. Most certainly don't use the 3rd one. A wild guess on my part is that the 3rd option was used and that's what made part of the drive "disappear" on you. I've not used it myself though to know that could happen. Hopefully this will help out.

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StreetHama

 
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Hi, thanks for your post. Not sure if that helps me really as I'm not trying to boot from my disk, I just want to see it, wipe it & reformat it. I will check the partition tonight though just in case.

Note: I'm in contact with the good people at mP4nation.net who are also trying to help me solve this:
http://mp4nation.net/forum/viewtopic.php?f=4&t=19107

They are trying to get hold of the original firmware so I can hopefully load that on & solve the problem. No one is quite sure if that will work but it will be worth a try.

Thanks for everyones time. Forums really are an amazing medium for people to help other people. It makes me think I should look at the Archicad forum because I might be able to help people on there...
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@lifeisabeach

Step 7 of that tutorial is the key. The problem occurs when folks use Disk Utility to format a flash drive or USB external drive to FAT-32. The default partitioning scheme is GUID; unless OPTIONS is selected and the MBR choice is made, the result will be two partitions: 1. EFI 200 MB 2. The remainder of the drive space.

Windows refuses to "see" past the first partition on external devices and therefore reports the drive as 200 MB rather then its full size. The only way to clear the drive and set it right is to use DISKPART from a command prompt in Windows and do an erase.

That isn't working for the OP. We've tried several times. For some reason the media drive he has won't show up in DISKPART but does show up in My Computer. It's a real head scratcher.

Regards.
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Hmmmph. On re-reading this thread, I see I did overlook a few things. Dangit I'm getting old.

Ok… so this was a media player that got reformatted. I'm wondering if the software on the player itself is corrupted or missing from reformatting it (which I imagine should never have been done in the first place). I'm trying to find some kind of support info on their website, but it's next to useless. I'm going to go out on a limb and suggest that perhaps the drive is only readable with the help of the player's software/hardware, and reformatting the device wiped out the software side.

That… or actually considering that the device and files appeared to be fine after formatting and copying files to it, then it was put in storage, and later found to be missing files and not working correctly… the drive or some other hardware has failed. Perhaps the drive had 2 internal flash drives… one at 700MB that has failed while in storage, the other 200MB one that is still working. Sitting out in the garage, I'm wondering what temperature extremes it may have been exposed to that it shouldn't have been.

EDIT: Ah nevermind. Now I see the OP said the player can still see both partitions. Sorry guys for muddling things up here… I'm having trouble following the original post for some reason.


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StreetHama

 
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The default partitioning scheme is GUID; unless OPTIONS is selected and the MBR choice is made, the result will be two partitions: 1. EFI 200 MB 2. The remainder of the drive space.

Can you please clarify the above. So if the GUID scheme is left as the default then you will end up with the two partitions as described?
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StreetHama

 
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Quote:
Originally Posted by chscag View Post

The default partitioning scheme is GUID; unless OPTIONS is selected and the MBR choice is made, the result will be two partitions: 1. EFI 200 MB 2. The remainder of the drive space.

Can you please clarify the above. So if the GUID scheme is left as the default then you will end up with the two partitions as described?
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StreetHama

 
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Quote:
Originally Posted by chscag View Post
When formatting flash drives using Disk Utility, you have to choose partitioning it as MBR not GUID. If you use the default format (FAT-32) and GUID, Disk Utility will create two partitions on the flash drive. One small 200 MB as EFI and the remainder FAT-32. That chokes Windows as it can't see past the first EFI partition and you'll wind up with a large flash drive with only 200 MB.

My recommendation for formatting any flash drive smaller than 32 GB is to use a Windows PC. (Disk Manager)

Regards.
I found this old post from 2008...
Clearly this is what I've done! Help someone please get me outta this!
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