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Formatting USB Drive = capacity shrinks?

Patrick J

Patrick J

macrumors 65816
Original poster
Mar 12, 2009
1,434
7
Oporto, Portugal
I have a USB Lacie iamaKey drive. It originally had a capacity of 8.09 GB (on Snow Leopard). I has been like that for months.

Today, I tried to format it with Disk Utility, and now the available space show up as 7.86 GB. I have tried deleting the partition, creating a new one, writing over with zeros, but I can, in no way, recover the lost space.

Why can I not use the maximum space of my drive?
 
Gameunreal said:
I have a USB Lacie iamaKey drive. It originally had a capacity of 8.09 GB (on Snow Leopard). I has been like that for months.

Today, I tried to format it with Disk Utility, and now the available space show up as 7.86 GB. I have tried deleting the partition, creating a new one, writing over with zeros, but I can, in no way, recover the lost space.

Why can I not use the maximum space of my drive?
Click to expand...

If this is an 8GB key, I think you had a bigger problem before. Normally 8GB keys only have 7.8 GB of space (8000/1024). Storage manufacturers always divide by 1000 instead of 1024 to make drives appear bigger. I have never seen a drive format with more than the indicated capacity, they all format at ~3% smaller than indicated.
 
I am aware of the Snow Leopard vs Windows/Leopard discrepancies, when regarding file sizes.

Regardless, is there any reason for me to be losing space?

Snow Leopard read the original space as 8.09 GB. Now is reads as 7.86.
 
FAT32. I have tried using Mac OS Extended Journaled with the same results.

Update: thanks to GGJstudios
I tried messing around with Options, under the Partition tab, and tried all 3: GUID, Apple Map, and MBR, and under MBR it now shows 8.07GB free space.

During all this time, under Disk Utility Total Capacity was stated as 8.09GB, so I was sure the space was there, just not being recognized correctly.
 
Gameunreal said:
FAT32. I have tried using Mac OS Extended Journaled with the same results.
Click to expand...

You may have already done this, but in case you haven't:
  • Launch Disk Utility and select the drive
  • Click on the Partition tab
  • Select Volume Scheme: 1 Partition
  • Click Options and select Master Boot Record
  • For Format, select MS-DOS(FAT)
  • Click Apply
 
I wonder if something in the partition is hosed, or there could be some bad parts of the disk.

If you check dmesg and other console logs, you should see the device it uses, say /dev/disk1.

You could wipe it out with dd in Terminal.

** NOTE **

I am not responsible if you delete data. You need to make very certain you are wiping the correct drive
 
GGJstudios said:
You may have already done this, but in case you haven't:
  • Launch Disk Utility and select the drive
  • Click on the Partition tab
  • Select Volume Scheme: 1 Partition
  • Click Options and select Master Boot Record
  • For Format, select MS-DOS(FAT)
  • Click Apply
Click to expand...

Worked perfectly. I updated above post to help future searchers. Thanks so much.
 
Gameunreal said:
Worked perfectly. I updated above post to help future searchers. Thanks so much.
Click to expand...

One other thing to remember is that FAT32 is limited to 4GB file sizes. As yours is an 8GB drive, this may or may not be a concern. If you want the ability to store a file larger than 4GB, re-format the drive to NTFS, which is what I use for any drive that is shared between Mac and Windows.

 
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