Wednesday, June 20, 2018

PocketBeagle - How to increase root filesystem size


If you are reading this, probably you already created your microSD card for the PocketBeagle which is recommended to be 4GB or bigger. But, regardless of the size of the microSD card you used the system image that got written on it has a fixed size that is most probably less than the total capacity of the card.

In my case, I used a 16GB microSD card, lets see how much is used …

debian@beaglebone:~$ df -v
Filesystem     1K-blocks    Used Available Use% Mounted on
udev              220048       0    220048   0% /dev
tmpfs              49624    5592     44032  12% /run
/dev/mmcblk0p1   3357264 1659656   1507352  53% /
tmpfs             248112       0    248112   0% /dev/shm
tmpfs               5120       0      5120   0% /run/lock
tmpfs             248112       0    248112   0% /sys/fs/cgroup
tmpfs              49620       0     49620   0% /run/user/1000

As you can see the total size of the root file system is about 3.3GB and 53% is already used !

Then, how can you increase the size to use the total available capacity on the microSD card ?

The process is similar on other BeagleBoards and actually on many Linux distributions, on the PocketBeagle is very simple since there is only one “memory block” device /dev/mmcbkl0

debian@beaglebone:~$ ls -l /dev/mmc*
brw-rw---- 1 root disk 179, 0 Mar  5 07:12 /dev/mmcblk0
brw-rw---- 1 root disk 179, 1 Mar  5 07:12 /dev/mmcblk0p1

For the next few operations you will have to become the superuser (root,) instead of having to enter each command preceded by sudo, you can just do sudo -I which will give you the shell in root mode

debian@beaglebone:~$ sudo -i

We trust you have received the usual lecture from the local System
Administrator. It usually boils down to these three things:

    #1) Respect the privacy of others.
    #2) Think before you type.
    #3) With great power comes great responsibility.

[sudo] password for debian:
root@beaglebone:~#

Notice that after entering the password now the command prompt changed from $ to #, you are now in superuser mode.

To increase the size of the partition and filesystem, first we’ll have to check the partition table and delete the current partition (don’t worry it does not delete the contents) and create a new partition with the new size.

root@beaglebone:~# fdisk /dev/mmcblk0

Welcome to fdisk (util-linux 2.29.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.


Command (m for help): p
Disk /dev/mmcblk0: 14.9 GiB, 15931539456 bytes, 31116288 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x0736b542

Device         Boot Start     End Sectors  Size Id Type
/dev/mmcblk0p1 *     8192 6963199 6955008  3.3G 83 Linux

Command (m for help):

Take note on with sector the partition says it starts, in this case 8192.

Now we will delete the existing partition and create a new one starting at the same sector but we’ll change where it ends, you can choose a smaller number than the total available sectors but I will chose the default which will give me all the available space on the current microSD card

Command (m for help): d
Selected partition 1
Partition 1 has been deleted.

Command (m for help): n
Partition type
   p   primary (0 primary, 0 extended, 4 free)
   e   extended (container for logical partitions)
Select (default p): p
Partition number (1-4, default 1): 1
First sector (2048-31116287, default 2048): 8192
Last sector, +sectors or +size{K,M,G,T,P} (8192-31116287, default 31116287):

Created a new partition 1 of type 'Linux' and of size 14.9 GiB.
Partition #1 contains a ext4 signature.

Do you want to remove the signature? [Y]es/[N]o: n

Command (m for help):

Notice that it now says the size of the Linux partition is 14.9 GiB !

No need to delete the signature, but we have not written yet the new partition table on the microSD card, we can double check the new parameters printing the new partition table

Command (m for help): p

Disk /dev/mmcblk0: 14.9 GiB, 15931539456 bytes, 31116288 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x0736b542

Device         Boot Start      End  Sectors  Size Id Type
/dev/mmcblk0p1       8192 31116287 31108096 14.9G 83 Linux

What we want, all the available space on the microSD card as the Linux partition, then we are ready to write the table

Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Re-reading the partition table failed.: Device or resource busy
The kernel still uses the old table. The new table will be used at the next reboot or after you run partprobe(8) or kpartx(8).

As soon as we wrote the new partition the Linux kernel detects that it has changed and we’ll have to reboot so it can load the new table

root@beaglebone:~# reboot

You will obviously lose your connection to the board if you are connected via ssh, then wait for the board to reboot then restart the connection, login and become root with sudo -i

login as: debian
debian@192.168.7.2's password:
Linux beaglebone 4.9.82-ti-r102 #1 SMP PREEMPT Thu Feb 22 01:16:12 UTC 2018 armv7l

The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
Last login: Mon Mar  5 07:31:39 2018 from 192.168.7.1
debian@beaglebone:~$ sudo -i
[sudo] password for debian:
root@beaglebone:~#

Before you do anything else we need to finish the process by extending the size of the filesystem with resize2fs, we’ll use the device that points to the first partition /dev/mmcblk0p1

root@beaglebone:~# resize2fs /dev/mmcblk0p1
resize2fs 1.43.4 (31-Jan-2017)
Filesystem at /dev/mmcblk0p1 is mounted on /; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 1
The filesystem on /dev/mmcblk0p1 is now 3888512 (4k) blocks long.

Let’s check then how much space we have now

root@beaglebone:~# df -v
Filesystem     1K-blocks    Used Available Use% Mounted on
udev              220048       0    220048   0% /dev
tmpfs              49624    4960     44664  10% /run
/dev/mmcblk0p1  15247576 1662340  12914392  12% /
tmpfs             248112       0    248112   0% /dev/shm
tmpfs               5120       0      5120   0% /run/lock
tmpfs             248112       0    248112   0% /sys/fs/cgroup
tmpfs              49620       0     49620   0% /run/user/1000

There you go, now we have all the available space on the microSD card and we have only 12% used, enough to download some updates/upgrades and packages for development.

Essentially the same process is used to increase the size of any Linux partition but you must be very careful if you have more than one partition on the table since they can’t overlap and by changing the table and resizing the filesystems you may lose the data if not done properly.


So, what’s next ? Connecting to the Internet ? why not ?

How to coming soon !

Cheers
Jorge


Wednesday, May 23, 2018

Raspberry Pi - ECN001 Hardware Mod

Update 5/23/18:
I published this article several years ago. No doubt many of the links and references are now outdated. Just keeping it here to preserve the history of some blog entries. 


Sunday, May 20, 2018

Update in progress ....

Many years ago I started using these Blogs to record and to share what I learned from my R&D work in technology particularly Digital Electronics or Embedded Design.

Also one of my hobbies has been what may be called "Retrocomputing" sort of having a little fun with old computers, some electronics tools and gadgets.

Due to time constraint I sort of abandoned the practice of writing new articles and updating these Blogs. Well I decided that it is time to get back and refresh this corner on the websphere reorganizing these pages and getting back into the habit to write new articles and keep this updated.

To have the content somehow organized I will keep three associated but specifically focused Blogs.


Some of these pages had some previous articles, some of them I put them in draft mode so I can check and update their content and republish.

I continue to generate a daily digital News Paper called Short Circuit that is generated automatically from various feeds I provide. I will also be updating those sources for more rich contact.

To those that have been writing me asking about old projects and when I'd be back... well this is the answer :-)

Hope you enjoy the content and feel free to provide your comments and contact me

Cheers
Jorge