============================== OLD Boot Raspberry Pi from USB ============================== .. include:: ../../donotuse.rst So why keep this? History... Posterity? Because I can? This how-to will show you how to begin using an external USB device - say a USB thumb drive or an External HD - as, not the "boot" device, but rather the storage location for the system files. ------------------ Find the USB Drive ------------------ If you're using a simple low-powered thumb drive, simply plug it into the Raspberry Pi. If you're planning on using a larger, HDD-like drive, I would suggest you use an externally powered USB hub device - to help power the external drive and not draw too much from the Raspberry Pi. Next, type ``lsusb`` to see a basic break down of what your RPI can see. It doesn't exactly get you a lot of info, but it doesn't hurt to start here. Usually, I see: .. code-block:: bash Bus 001 Device 004: ID 0930:6545 Toshiba Corp. Kingston DataTraveler 102 Flash Drive / HEMA Flash Drive 2 GB / PNY Attache 4GB Stick Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp. SMSC9512/9514 Fast Ethernet Adapter Bus 001 Device 002: ID 0424:9514 Standard Microsystems Corp. Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub The top line being the flash drive that I have plugged in. But, you'll notice, it doesn't give you the nice pretty ``/dev/sd[x]`` that we're needing here. Now, the website I'm using as a guide for this instructional [AFRUIT-USB]_ suggests using ``dmesg`` as a way to find your device. Though this can be messy because ``dmesg`` is basically your systems "this is what I'm doing and seeing all the time" kind of messaging service. Anytime a USB device is plugged or unplugged, anytime you start, stop or restart your machine, or any number of events occurring, it adds itself to ``dmesg``. So, don't get flustered if you can't find your USB device. If the last thing you did was insert your USB, it should be the last item appearing on ``dmesg`` Using ``sudo dmesg`` should show something resembling: .. code-block:: bash [ 459.896922] usb 1-1.2: new high-speed USB device number 4 using dwc_otg [ 460.018734] usb 1-1.2: New USB device found, idVendor=0930, idProduct=6545 [ 460.026951] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber=3 [ 460.035530] usb 1-1.2: Product: TransMemory-Mx [ 460.041271] usb 1-1.2: Manufacturer: TOSHIBA [ 460.046801] usb 1-1.2: SerialNumber: 60A44C429E6BED81F000ED00 [ 460.055140] usb-storage 1-1.2:1.0: USB Mass Storage device detected [ 460.064034] scsi host0: usb-storage 1-1.2:1.0 [ 461.068295] scsi 0:0:0:0: Direct-Access TOSHIBA TransMemory-Mx PMAP PQ: 0 ANSI: 6 [ 461.081327] sd 0:0:0:0: [sda] 60929280 512-byte logical blocks: (31.2 GB/29.1 GiB) [ 461.093654] sd 0:0:0:0: [sda] Write Protect is off [ 461.100343] sd 0:0:0:0: [sda] Mode Sense: 45 00 00 00 [ 461.101667] sd 0:0:0:0: [sda] Write cache: disabled, read cache: enabled, doesnt support DPO or FUA [ 461.114459] sd 0:0:0:0: Attached scsi generic sg0 type 0 [ 463.171778] sda: sda1 [ 463.182905] sd 0:0:0:0: [sda] Attached SCSI removable disk You'll notice the ``sda`` monikers there. That would be the ``/dev/sda`` that we're looking for. So, the newest USB device has been assigned ``/dev/sda`` on my machine. Now, of course, yours might be different. You never know. Or, if you're ``dmesg`` is stupidly long and you can't find it quickly, you can always ``sudo dmesg | grep sd[a-z]`` .. note:: ``grep`` being a searching program and the ``sd[a-z]`` being whats called a "regex" search. Basically, grep takes ``sd`` then adds each letter from a-z to the end and searches for those terms. It then will present you with the information, making it easier for you to find things. The same thing works with ``[0-9]`` as well. I like to use it to delete a large amount of log files that tend to build up inside of ``/var/log``. ``sudo rm ./*.[0-9].*`` or what have you. ------------------------------ Install Adafruit's USB Program ------------------------------ This specific program they've written automates the wiping and partitioning of the USB drive, moving of the system files, and setting up the boot files. Adafruit's ``apt-get`` Repo Script ========================================== So, to install it, you'll want to add Adafruit's Linux Repo to your apt-get stuffs. You can either: .. code-block:: bash curl -sLS https://apt.adafruit.com/add | sudo bash Which will automatically add their repo and do a ``sudo apt-get update`` for you. Or, you can go the long way round: ---------------------------------------------- Adafruit's Repo the Long Way Round ---------------------------------------------- - First, adding the repo to your ``sources.list.d`` .. code-block:: bash echo "deb http://apt.adafruit.com/raspbian/ jessie main" | sudo tee /etc/apt/sources.list.d/adafruit.list - Then, grabbing their gpg key: .. code-block:: bash wget -O - -q https://apt.adafruit.com/apt.adafruit.com.gpg.key | sudo apt-key add - - And then run ``sudo apt-get update`` Now, before we go to far, why don't we break all that down? 1. The ``echo deb http://apt.adafruit.com/raspbian/ jessie main`` part first - ``echo`` so that we can copy and pipe that quoted text - ``sudo tee`` is a way to take text thats been piped into it, and either overwrite or append that text to a file. In this case, overwrite to ``/etc/apt/sources.list.d/adafruit.list`` 2. The GPG Key - ``wget`` is a program to download things from the interwebs - ``-O - -q``: - the ``-O`` is for amending the output of the download - the ``-`` is saying the output is ``STDOUT``, or ``copy it to output so we can pipe it`` - the ``-q`` is a flag saying "run it quietly" or "no output preferred other than the file" - ``sudo apt-key add -`` is to add the downloaded key, and the ``-`` is saying "take the ``STDOUT`` from the ``wget`` and use that" ----------------------- Installing USB Program ----------------------- Next, you'll want to install Adafruit's USB program. .. code-block:: bash sudo apt-get install adafruit-pi-externalroot-helper ----------------------- Running the Program ----------------------- Then, once you know for sure the file location moniker of your USB device: .. code-block:: bash sudo adafruit-pi-externalroot-helper -d /dev/sda The ``-d`` flag is to tell it the file location moniker of your USB device. .. note:: Make SURE you get this right, as you don't want to really wipe your SD card. Though I'm fairly certain not only would that not work, it luckily is an easy fix to get either a clean OS on it, or a backup you've made. This program does take at least a few minutes to run through. You'll need to restart your RPI as well once its finished. ----------------------- After Running ----------------------- It will give you a series of messages once its done. Make sure to read through them, in case there are any errors. It also tells you how to make sure it worked: .. code-block:: bash [boot config] Ok, your system should be ready. You may wish to check: [boot config] /mnt/etc/fstab [boot config] /boot/cmdline.txt [boot config] Your new root drive is currently accessible under /mnt. [boot config] In order to restart with this drive at /, please type: [boot config] sudo reboot fstab ======== The key lines are: .. code-block:: bash Ok, your system should be ready. You may wish to check: /mnt/etc/fstab /boot/cmdline.txt It really means you need to check ``/etc/fstab``. Not sure why they included the extra ``/mnt`` in there. My ``/etc/fstab`` now shows: .. code-block:: bash /dev/mmcblk0p1 /boot vfat defaults 0 2 #/dev/mmcblk0p2 / ext4 errors=remount-ro,noatime,nodiratime,commit=120 0 1 tmpfs /tmp tmpfs defaults,nodev,nosuid 0 0 /dev/disk/by-uuid/94551cfd-d0fc-42df-b742-b7a6434c0d8a / ext4 defaults,noatime 0 1 Notice the commented out line ``#/dev/mmcblk0p2`` SD Card Info ================= That was the original line for the sd card. The line prior was also there before, as the SD card was both the boot media and the OS media. But, now the SD is ONLY the boot, and the external USB is the OS media. Running ``df -h`` ================= You can also ``df -h``. This shows your filesystem stuffs. The ``-h`` being human readable format on the sizes. .. code-block:: bash Filesystem Size Used Avail Use% Mounted on /dev/root 29G 1.2G 26G 5% / devtmpfs 483M 4.0K 483M 1% /dev none 4.0K 0 4.0K 0% /sys/fs/cgroup tmpfs 487M 0 487M 0% /tmp none 98M 232K 98M 1% /run none 5.0M 0 5.0M 0% /run/lock none 487M 0 487M 0% /run/shm cgmfs 100K 0 100K 0% /run/cgmanager/fs none 100M 0 100M 0% /run/user /dev/mmcblk0p1 61M 36M 26M 58% /boot tmpfs 98M 0 98M 0% /run/user/1000 The location ``/dev/root`` is the USB drive now. And, it shows the large size of the USB drive as well. -------------------------------- Recovering from a Failed Boot -------------------------------- If the RPI should ever not wanna work correctly with the USB drive this way, you can always: #. take the SD card out of your RPI, plug it into your regular machine that you used to install the OS. #. Then, open the first partition and find the file ``cmdline.txt``. #. Replace the text ``root=PARTUUID=....rootdelay=5`` with ``root=/dev/mmcblk0p2``, which will point the root partition back to the 2nd partition of your SD card. It should roughly look like this: .. code-block:: bash dwc_otg.lpm_enable=0 console=ttyAMA0,115200 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline rootwait fbcon=map:10 fbcon=font:VGA8x8 Then, place the SD card back into the RPI, and it should boot normally. .. [AFRUIT-USB] Adafruit's `Raspberry Pi on USB`_ .. _Raspberry Pi on USB: https://learn.adafruit.com/external-drive-as-raspberry-pi-root/hooking-up-the-drive-and-copying-slash