Unable to shrink root fs

[Zaxter]

I'm using Igor's ubuntu trusty image with kernel 3.4.105 (http://www.igorpecovnik.com/2014/11/18/olimex-lime-debian-sd-image/). This image auto-resizes the rootfs to occupy the complete SD card, on first login.

I have installed custom software onto this SD card, and now I want to clone it. But, I need to shrink the rootfs to 2GB before doing so.

Here's what I did:

• sudo fdisk /dev/mmcblk0


• Command (m for help): p
          Device Boot      Start         End      Blocks   Id  System
  /dev/mmcblk0p1            2048    15523839     7760896   83  Linux
  


• Command (m for help): d


• Command (m for help): n
  Partition type:
     p   primary (0 primary, 0 extended, 4 free)
     e   extended
  Select (default p): p
  Partition number (1-4, default 1): 1
  First sector (2048-15523839, default 2048):
  Using default value 2048
  Last sector, +sectors or +size{K,M,G} (2048-15523839, default 15523839): 7500000
  


• Command (m for help): p
  
          Device Boot      Start         End      Blocks   Id  System
  /dev/mmcblk0p1            2048     7500000     3748976+  83  Linux
  


• Command (m for help): w
  The partition table has been altered!
  


• reboot

However, the board doesn't boot up after this.

What am I doing wrong? I'm a newbie, please help.

[JohnS]

That looks to reduce the size for the fs but isn't re-making the fs i.e. moving data and its inode etc info, so corrupts it.

I'd use a loopback device of the size you want on a PC, copy data across file-by-file, remake the SD card and copy data back.

John

[Zaxter]

Thanks for your reply John. I will try as you have said.
For curiosity's sake, how is it that the above method works with raspberry pi?(http://elinux.org/RPi_Resize_Flash_Partitions#Manually_resizing_the_SD_card_on_Raspberry_Pi)

[JohnS]

I don't know if it works for shrinking.  It may, for a smallish change, but at some point it definitely won't.  There again I expect hardly anyone uses it for shrinking.

BTW, I didn't see where you ran resize2fs - did you try it?

John

[Zaxter]

I didn't run resize2fs. I thought that was supposed to be done after the reboot. (But my board didn't reboot at all.  )

Do you suggest running resize2fs before rebooting?

[Zaxter]

I tried resize2fs, but this still doesn't work:

Code Select Expand

root@micro:~# resize2fs /dev/mmcblk0p1
resize2fs 1.42.5 (29-Jul-2012)
The filesystem is already 1940224 blocks long.  Nothing to do!


The board keeps rebooting continuously.

[JohnS]

You're not doing it the way that link you posted does are you?

You'll have already corrupted things so will have to start over.

John