Recover Unallocated Space on SD card

I used RiscOS for a couple of days and then decided it wasn’t nearly as useful as Linux. So, I decided to write over the SD card containing RiscOS.

I tried using WinImage but for some reason the card refused to write. I had a lovely cyclic redundancy check error and the SD card was reporting the wrong amount of space free.

I tried using the Disk Management tool in Windows but it wouldn’t let me expand the primary partition to the full space.

I found this tutorial about using DiskPart to reset the card:

Recover Missing Unallocated Space On USB Drive Using Windows DiskPart.

In short:

  1. Press Windows-R and type DiskPart in the ‘Open’ box.
  2. This will bring up a DOS box with DiskPart running in it.
  3. Type ‘list disk’ and look for the disk that resembles your SD card. (For this tutorial, we’ll assume it’s Disk 1)
  4. Type ‘select disk 1’
  5. BE REALLY SURE YOU WANT TO WIPE THE CARD.
  6. Type ‘clean’. This resets the disk.
  7. Type ‘create partition primary’
  8. Type ‘exit’ to quit.

You can now go into Windows Explorer and Format the SD card before writing your image to it.

22 comments for “Recover Unallocated Space on SD card

  1. Your an absolute legend, thanks very much for this info my sd card is now working again and I can see it’s full storage!

  2. ive enounter this error what should i do diskpart has encountered an error data error cyclic redundancy check

  3. Thanks, am a beginner if i could rate myself but i followed everything and it worked perfect.

  4. after step 6 he told me
    “disk part has encountered an error : the device is not ready.
    see the system event log for more information ”
    so what should i do now ???

    • Take a look at the system logs – /var/log/syslog and /var/log/messages
      Also make sure the write protect switch on the card hasn’t moved to to the wrong position.

  5. i am trying to execute Diskpart command in my sd card to remove wright protected….. but after ‘create partition primary’ i found some unwanted error….. please help me

  6. Help me to short our this problem.. during diskpart command……

    DISKPART> create partition primary

    No usable free extent could be found. It may be that there is insufficient
    free space to create a partition at the specified size and offset. Specify
    different size and offset values or don’t specify either to create the
    maximum sized partition. It may be that the disk is partitioned using the MBR di
    sk
    partitioning format and the disk contains either 4 primary partitions, (no
    more partitions may be created), or 3 primary partitions and one extended
    partition, (only logical drives may be created).

  7. Today i partitioned my sd card by minitool partition app. Very few space in sd card is workable which is primary @ fat32, and huge amount of space is unallocated.
    I try to restore the sd card in many ways. In which one way is that you mentioned above. Using your way commond promt replies as below ::::::

    No usable free extent could be found. It may be that there is insufficient
    free space to create a partition at the specified size and offset. Specify
    different size and offset values or don’t specify either to create the
    maximum sized partition. It may be that the disk is partitioned using the MBR di
    sk
    partitioning format and the disk contains either 4 primary partitions, (no
    more partitions may be created), or 3 primary partitions and one extended
    partition, (only logical drives may be created).

  8. Hi! I just ran into the “unallocated space” issue with a 32gb micro sdhc card. It was showing 1.46 gb healthy partition and 29gb unallocated space. Tried to use the DiskPart utility and it gave me the error access is denied see system log. The system log shows that it could not zero sectors on disk. The 1.46gb of space are no longer there and i’m left with the 29gb of unallocated space. Is this little card pooched? thnx!

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