I have a Raspbian Jessie installation where
mmcblkp01 is not mounted. During boot I see this message on the console:
start job running for `dev-mmcblk0p1.device`
Eventually this times out and I am dropped into the emergency mode. When I enter the root password I can mount
mmcblk0p1.device without a problem:
mount /dev/mmcblk0p1 /boot
The line in
/dev/mmcblk0p1 /boot vfat defaults 0 2
mmcblk0p1 is a normal VFAT partition. The start and end sectors are equal to a working Raspbian installation.
If it is relevant,
sysctl cannot start
Now I can take the easy way and make a fresh install, but I want to understand why this happens. So the main question is, where can I start to search why
mmcblk0p1 is not mounted? Or why the
dev-mmcblk0p1.device service is not started.
How I ended up here:
Some background information. Raspbian did not start to refuse mounting mmcblk0p1 all by itself. This is the history:
- I had a working Raspbian Wheezy installation
- Dist-upgraded that to Jessie (still no problem)
- Mounted a USB external hard disk as root file system
- Changed cmdline.txt to use the USB disk as root file system
/etc/fstabto mount the USB disk on '/' instead of
I did not touch anything related to
mmcblk0p1 or the boot partition or whatever. When mounting a different device as a root file system there must always be a boot partition on the SD card. That is how the Pi works.
This installation worked all fine. I need the HDD because I am running a data logger on a MySQL database and I don't want to wear out the SD card.
Next, I made a full rsync copy of the installation.
The Pi with USB HDD went into production
But I need a shadow system to continue testing and development
This time without external HDD because the Pi is not running continuously. The development Pi had a Wheezy install.
I took out the SD card from the Pi and mounted it on my desktop machine.
sdc2 -> /mnt/pi-root sdc1 -> /mnt/pi-root/boot
Rsync-ed the previously made image to the SD card. Modified
/etc/fstab to the normal original versions as for using the SD card as root FS.
Placed the SD card back in the Pi and then the problem occurred.
I just want to understand why
mmcblk0p1 is not mounted. I am sure I can solve the problem to get a working system back. But for future projects I want to know how I can clone a production system back into a development system.