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I wish to reformat my SD card to use normally again (it currently has one 78MB FAT32 partition and one 3.9GB Linux partition). How do I do this (on Windows/Mac/*nix)?

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Well it worked for me on W7..Thanks much –  user6769 Apr 4 '13 at 4:16
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7 Answers 7

up vote 29 down vote accepted

You can use DISKPART in Windows, or the equivalent fdisk command under Linux/Mac.


DISKPART (Windows)

Start a command prompt, and start the DISKPART console. List all of your disks by typing LIST DISK, then select the proper disk with SELECT DISK # (where # is obviously the SD card). You can then type CLEAN (MAKE SURE YOU SELECTED THE PROPER DISK!), and it will clear the partition table on the card.

To create a primary partition to reuse the space on the card, type CREATE PARTITION PRIMARY. This will then reallocate the previously "cleaned" space.

To format, type FORMAT FS=FAT32 QUICK, and finally, to reassign a drive letter, type ASSIGN.

If you're unable to determine the proper disk, remove the SD card, run DISKPART and LIST DISK, and then re-run it with the SD card inserted. The SD card is just the disk that has been added.


FDISK / CFDISK (Linux/Mac)

In a terminal, start fdisk /dev/sdx where /dev/sdx is your SD card device (may depend on the Linux distro you're using, see below). You can then delete all existing partitions on the device by typing d, and then adding a single new partition & format it. You an also just type n to create a new partition table, and start laying everything out.

cfdisk is also another viable tool, which is basically fdisk with a greatly improved user interface. In both cases, once the drive is formatted, you will lastly need to mount it.

If you're unable to determine the proper device, remove the SD card, run fdisk -l, and then re-run it with the SD card inserted. The SD card is just the device that has been added.

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@AlexChamberlain in DISKPART, you can generally tell by the capacity of the disk. Once you select a disk, you can also call LIST VOLUME to see all the drive volumes and their labels (so long as your SD card's name shows up, you have the right device). If you're using fdisk, type p to print the partition table and check that the volume labels are correct. If you're using cfdisk, it should show you the volume labels right after you start the command on a device. –  Breakthrough Aug 4 '12 at 14:12
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Sounds good! Let's delete this comment thread to clean up! –  Alex Chamberlain Aug 4 '12 at 14:26
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On your camera

Most cameras have a built in Format function, which will use a single FAT partition. My camera even puts it on an erase block boundary.

For example, on my Pansonic Lumix, having inserted the card and from any mode, the menu as a Format entry. Selecting it brings up a menu asking me to confirm I wish to delete all the data on the card. Selecting Yes formats the card.

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:) It will be one FAT partition, starting at the second erase block. –  Alex Chamberlain Aug 4 '12 at 19:47
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It'll be FAT Formatted like any other FAT formatted device… it's not camera specific. However, he'll have to delete various folders created like "DCIM" –  XAleXOwnZX Aug 4 '12 at 22:38
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You can use the official SDCard.org application (Windows / Mac).

https://www.sdcard.org/downloads/formatter_3

It's fairly simple and reformats the SDCard in FAT32. There are options for LBA-adjustment and wiping / erasing as well.

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There are some specific tools for SD cards only but I like to use EaseUS Partition Tool which is free for Windows users. It will not work on Server Editions. * Please be aware that apparently they are bundling some software. Click on advanced options to prevent this

You should take care to select your SD card from the list of devices as this tool will list all your drives. This shows how to resize a parition.

enter image description here

  • Best bet is to complete delete any partitions on the SD card. This will include FAT and EXT and possibly a SWAP. Just delete them so you can see a full unallocated 16GB.
  • No operations will be performed until you click APPLY. Once you have removed all partitions follow instructions to reload the distro you like.

Hardware Error

If, however in the list you see your card listed as 55mb in total size and have no option to remove or expand it more that means the SD card is broken. There is no way to fix it and happens sometimes. Something fried the controller so you will need a new one or send that one off on warranty.

Example

This is my 4GB Rasbpian SD card. I used Windows management tools. Yes it shows it but it wont let you do anything to the partitions just in case ... you delete it or Windows corrupts something (Because it does not support that file system)

enter image description here

EaseUS partition master shows a much better list and understands that file systems used. Right click and delete the partitions. You can create new partitions too and apply everything and you will have the whole SD card back to use in Windows or if you want to burn another image to the card.

enter image description here

Here I have deleted the partitions. Right clicked ans said create new partition. There is a whole list of file system types. I did not click apply so no operation has been done yet.

enter image description here

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this program tries to install a number of other applications when you install it. –  Phil Vallone Jun 7 at 0:05
    
Sorry when i wrote this that wasnt an issue. I have updated my anser to warn about this. I still feel its good software and I hope the downvote will be removed. –  ppumkin Jun 9 at 8:17
    
Done - but I wouldn't install it. My Anti-virus software was blocking a ton of stuff from being installed. –  Phil Vallone Jun 9 at 10:42
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Currently, one of the best disk management utils seems to not have been mentioned - GParted:
pic of GParted

This is included in many Linux distros, and can be installed easily otherwise. For other systems, it is possible to run it off of a DVD or USB stick, so it can be used there as well. The Linux part also means it supports the SD card format if it is ext*, so it can be reformatted easily and efficiently, and less problems are likely to occur. Most disk utils, particuarly on Windows, will likely destroy any boot data on the SD card and muck it up in other ways.

Here a screenshot of GParted showing the contents of an SD card with Raspbian on:
screenshot of GParted
Note: The boot partition will likely have a label or flag 'boot'

To carry out operations on a partition of an, right click on it, and select 'Unmount'. If a partition is mounted (shown by a set of keys next to the partition name), no operations can be done on it. Once it is unmounted, you can check it for errors, reformat it, rename it, delete and create a new one, etc.

Documentation on using GParted can be found here

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I had a very similar issue. My set up: Computer running on Windows 7 and Sandisk ultra card 16GB.

I wanted to format my card for installing Open Elec. So I downloaded SD formatter and tried formatting it. It became a 64 MB card! Tried multiple settings, tried diskpart on CMD and clean format using computer management/disk management console - no luck. Always winimg writer claimed there was no sufficient space in the card. Earlier (that is before using SD formatter) it will expand the space and will install and I subsequently used expand command on Rpi terminal. So here is what I did:

Downloaded berryboot (note it is 28 mb!) wrote the image on SD card and booted the Rpi. Berry Boot reformatted the same using its own in built prgm. Now I took the card out and formatted it using the format tool on windows with FAT. Took the card out and re inserted. Now it reads 14.4 GB! Any one stuck like this can try this out.

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Windows will only see the small header partition that is left over when the card is formatted to Linux compatibility. So the card is still the same size, its just that windows cant understand the Linux parition and so completely ignores its existance. Much like linux does with that header partition. –  Phill Healey Jan 23 at 11:47
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No good on Mac with latest OSX. Card cant be erased in any way.

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Nonsense, what about fdisk? –  Jivings Mar 29 '13 at 9:34
    
@Jivings since I can't edit (due to my FAQ spree), how should I respond to this question while reviewing: flag, comment, etc? –  xxmbabanexx Mar 30 '13 at 5:47
    
@xxmbabanexx Downvote probably. It is an answer, it's just wrong. And that's not a flaggable offense. –  Jivings Mar 30 '13 at 9:01
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