Ubuntu storage expansion guide

I have hacked together a storage expansion system for Ubuntu, similar to the one in the default Linpus.

Unlike the Linpus version however, it expands the whole filesystem, not just the user home folder, this means that the extra space can be used for program installation, multiple users, etc.

Preparation
Unlike the Linpus version, my system requires that the SD card be formatted with the ext2 filesystem (it also expects the OS to be installed on ext2).
To do this, fire up a terminal and type:

Code:

sudo mkfs.ext2 /dev/mmcblk0p1

We will also need the aufs-tools package:

Code:

sudo apt-get install aufs-tools

Installation
First download the script from here: http://www.xeonplus.net/mfh/download.php?file=609rootaufs (sorry about the sucky download system).
Now, copy the script the the required location:

Code:

sudo cp /path/to/dowload /etc/initramfs-tools/scripts/init-bottom/rootaufs

Then set the security rights:

Code:

sudo chown root /etc/initramfs-tools/scripts/init-bottom/rootaufs
sudo chmod 755 /etc/initramfs-tools/scripts/init-bottom/rootaufs

Now, since this script runs long before SD card support is normally loaded, we must change this:

Code:

sudo -s
echo mmc_core >> /etc/initramfs-tools/modules
echo mmc_block >> /etc/initramfs-tools/modules
echo sdhci >> /etc/initramfs-tools/modules

And, since we are using aufs:

Code:

echo aufs >> /etc/initramfs-tools/modules
exit

Finally, we must update the initramfs:

Code:

sudo update-initramfs -u

Usage
To enable the script, add "aufs=on" to the end of the "kernel" lines in /boot/grub/menu.lst by running:

Code:

sudo gedit /boot/grub/menu.lst

It is probably also best to add it to the end of the #defoptions line.

After this, reboot. When the system comes back up, check the output of:

Code:

cat /proc/mounts

If you see a line like:

Code:

aufs /dev/.static/dev aufs rw,relatime,xino=/sd/.aufs.xino,create=mfs:30,br:/sd=rw:/ssd=rw 0 0

Then it (probably) worked.

The filesystem is now layed out as follows:

• /sd - the SD card
  /ssd - the SSD
  / - the combined filesystem.

If you ever need to edit/create files on a specific filesystem (e.g. the files in /boot should always be on the SSD) prefix the paths as above (e.g. /boot/grub/menu.lst is /ssd/boot/grub/menu.lst).

Credits
The script is based heavily on the one shown here: https://help.ubuntu.com/community/aufsRootFileSystemOnUsbFlash
Some additional documentation found here: http://aufs.sourceforge.net/aufs.html

Any questions? Corrections? Problems? Improvements? Let me know.

 

Whoops, have discovered that some "interesting" things happen if you boot with an SD card in the other slot!
To prevent this, first boot up without another SD card, then:

Code:

ls -l /dev/disk/by-uuid/

Will give a listing like this:

Code:

lrwxrwxrwx 1 root root 15 2008-08-28 22:05 e2ef0737-45d2-406a-9c6d-1136362670fd -> ../../mmcblk0p1
lrwxrwxrwx 1 root root 10 2008-08-28 22:05 e4ed8e21-5328-4fa1-a9fe-7e59a01163fa -> ../../sda1

Copy the UUID that points to mmcblk0p1 (e2ef0737-45d2-406a-9c6d-1136362670f in my case).

Then edit the script (sudo gedit /etc/initramfs-tools/scripts/init-bottom/rootaufs) on line 123 change:

Code:

mount -t ext2 /dev/mmcblk0p1 /sd -o noatime

to:

Code:

mount -t ext2 /dev/disk/by-uuid/your-uuid /sd -o noatime

Save and quit.
Delete the backup to avoid cluttering the initramfs, then update it:

Code:

sudo rm /etc/initramfs-tools/scripts/init-bottom/rootaufs~
sudo update-initramfs -u

If you are running an extended FS, make sure the initramfs is on the SSD by typing:

Code:

sudo mv /boot/initrd.img-<your-kernel-version> /ssd/boot/initrd.img-<your-kernel-version>

 

Will this work after suspend/resume or will it erase SDHC partitions as stock ubuntu?

I am currently using a 16Gb SDHC as my home partition, and I cannot use suspend/resume due to this problem.

 

I second this question. There was another post that recommended CONFIG_MMC_UNSAFE_RESUME=y in a custom kernel config to fix the suspend/resume. Does aufs not need this?

 

I see a previous poster here indicated they used a hi capacity SD card.

Can anyone confirm that you can use SDHC cards in the card readers in the ZG5 model?

 

To anwer my own question - yes. I just bought an 8GB SDHC and this works fine, but I have noticed the disk dissappears after suspend, and wireless fails to com back after hibernate. Oh well, it only takes about 80 seconds to boot from cold and log in anyway 8) (still longer than linpus's 15 seconds, but atleast I can install the apps I need easily in Ubuntu.

 

can this script be use with the latest version of Ubuntu ? Hopefully it works, so that i donot have to upgade my aa1 with a bigger SSD or modded with hard disk.

I am going to isntall Ubuntu 8.10 UMPC version.

Please advise, thanks.