RPi Resize Flash Partitions

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Revision as of 00:18, 18 September 2012 by Stokestack (talk | contribs) (Added the instructions to unmount the partition if you can't resize it.)
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The prepared images of the raspberry are created for SD cards of the size of 2GB. The SD card can be resized to use the full size of a SD card that is greater than 2GB. This page explains how to format the SD card to use the full size of it.


You might want to backup your SD before resizing partitions. Windows-Users may use the HDD Raw Copy Tool

Manually resizing the SD card on Linux

Tutorial video here: http://www.youtube.com/watch?v=R4VovMDnsIE

Following on from the instructions above, keep the newly-written SD card in the card reader, but unmounted. We'll use the parted (partition editor) tool to resize the partitions.

  • Show partition information to find your SD card

$ df -h

Look for a partition that matches the roughly 2GB size of your distribution image.

  • Unmount the partition

$ umount /dev/sdc2

  • Use parted to examine the card
$ sudo parted /dev/sdd
(parted) unit chs
(parted) print
Disk /dev/sdd: 121535,3,31
Sector size (logical/physical): 512B/512B
BIOS cylinder,head,sector geometry: 121536,4,32.  Each cylinder is 65.5kB.
Partition Table: msdos

Number  Start      End         Type     File system     Flags
 1      16,0,0     1215,3,31   primary  fat32           lba
 2      1232,0,0   26671,3,31  primary  ext4
 3      26688,0,0  29743,3,31  primary  linux-swap(v1)
This shows how my SD card was formatted after writing the image. Notice that nothing uses the card from end of 'cylinder' 29743 to the card's maximum at 121535.
Partition 1 is the boot partition: we'll leave that alone. Partition 2 is the root partition, which we'll grow to fill most of the card. Some OS versions will have a Partition 3 for swap space, which needs to be moved to the end of the card. Note that on some other versions of linux (and some other versions of hardware) use /sde not /sdd.
  • Move the swap partition if it exists (you'll have to adjust the numbers so that the end of partition 3 is at the end cylinder/head/sector of the card)
  • to calculate the number to use in the following command do:- (Maximum - (Partation 3 End - Partation 3 Start) ) - 1 = Partition 3 New Start so in this example (121535 - ( 29743 - 26688)) -1 = 118479
  • Will not work with parted versions later than 2.4
(parted) move 3 118479,0,0
  • Now grow the root partition. This involves removing the partition, re-creating it, then using resize2fs to grow the filesystem to fill the partition. It won't destroy any data.
(parted) rm 2
(parted) mkpart primary 1232,0,0 118478,3,31
(parted) quit
Note that the starting address of the new partition is identical to its original value, and the ending address is immediately before the start of the swap partition.
  • Now clean and resize the root partition. As before, some users may need to use /sde2 instead.
$ sudo e2fsck -f /dev/sdd2
(allow it to add lost-and-found)
$ sudo resize2fs /dev/sdd2
  • Then put the card in the RPi and boot. You end up with a 7Gb partition to use.
pi@raspberrypi:~$ df -h
Filesystem            Size  Used Avail Use% Mounted on
tmpfs                  94M  4.0K   94M   1% /lib/init/rw
udev                   10M  168K  9.9M   2% /dev
tmpfs                  94M     0   94M   0% /dev/shm
rootfs                7.1G  1.3G  5.4G  20% /
/dev/mmcblk0p1         75M   28M   48M  37% /boot

Manually extracting partitions from the image on Linux

Get the information about offsets and sizes from the SD-Card-Image:

$ parted -s SD-Card-Image unit KiB print

Here, the -s option directs parted to go into scripting mode and the commands unit KiB print tells parted to display its results in blocks of 1024 byte (KiB, see also block size in GNU Coreutils docu) and print the partition table.

You will get some information like the following (this is created with the Raspbian Wheezy image dated 15-Jul-2012):

Disk SD-Card-Image: 1894400kiB
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number  Start     End         Size        Type     File system  Flags
 1      4096kiB   61440kiB    57344kiB    primary  fat16        lba
 2      61440kiB  1894400kiB  1832960kiB  primary  ext4

Now you can extract the partitions with

 $ dd if=SD-Card-Image of=Part1 bs=1024 skip=4096 count=57344
 $ dd if=SD-Card-Image of=Part2 bs=1024 skip=61440 count=1832960

Fill in the skip and count parameters with the numbers for start and size, which you got from the parted command above.

Manually resizing the SD card using a GUI on Linux

If you are using a PC with a linux distribution to resize the partitions, you can run GParted to resize the partitions using a GUI. This method is tested on Ubuntu 10.10 using the Gnome desktop. Versions of GParted differ slightly in their GUIs.

GParted can be installed using:

  • sudo apt-get install gparted

Note: I had to physically remove and re-insert the SD card from the card reader after writing the image before the partitions were recognised properly and the following could be done.

  • Start GParted (on my system it is [System]->[Administration]->[GParted Partition editor]).
  • Select the drive corresponding to your SD card (was /dev/sdh/ on my system). You now see the partitions mentioned above (with some tiny unallocated areas in between and a large one after).
  • Select the swap partition by clicking on it.
  • If the Resize/Move toolbar icon or [Resize/Move] menu option is disabled, go to Partition / Unmount.
  • Select the menu option [Partition]->[Resize/Move] and drag the partition to the right (click/drag in the middle).
  • Select the ext4 partition.
  • If the Resize/Move toolbar icon or [Resize/Move] menu option is disabled, go to Partition / Unmount.
  • Resize the partition by dragging the right edge of the partition all the way to the right (click/drag the right edge).
  • When you are satisfied with the changes, click on the green check mark, "Return" arrow, or other "apply" control to execute these changes.

You're done!

Manually resizing the SD card on Raspberry Pi

You can also resize the partitions of the SD card that your Pi is running on.

First you need to change the partition table with fdisk. You need to remove the existing partition entries and then create a single new partition than takes the whole free space of the disk. This will only change the partition table, not the partitions data on disk. The start of the new partition needs to be aligned with the old partition!

Start fdisk:

sudo fdisk -cu /dev/mmcblk0

Then delete partitions with d and create a new with n. You can view the existing table with p.

  • p to see the current start of the main partition
  • d, 3 to delete the swap partition
  • d, 2 to delete the main partition
  • n p 2 to create a new primary partition, next you need to enter the start of the old main partition and then the size (enter for complete SD card). The main partition on the Debian image from 2012-04-19 starts at 157696, but the start of your partition might be different. Check the p output!
  • w write the new partition table

Now you need to reboot:

 sudo shutdown -r now

After the reboot you need to resize the filesystem on the partition. The resize2fs command will resize your filesystem to the new size from the changed partition table.

sudo resize2fs /dev/mmcblk0p2

This will take a few minutes, depending on the size and speed of your SD card.

When it is done, you can check the new size with:

df -h