From Fedora Project Wiki

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# Open terminal
# Open terminal
# Switch to root user: <code>su -</code>
# Switch to root user: <code>su -</code>
# if needed make a bachup of /home on your root filesystem.
# if needed make a backup of /home on your root filesystem.
# comment /home out in your /etc/fstab
# comment /home out in your /etc/fstab
# unmount /home: <code>umount /home</code>
# unmount /home: <code>umount /home</code>

Revision as of 07:12, 12 October 2013


This page describes a test case for bcache-tools, Bcache is a Linux kernel block layer cache. It allows one or more fast disk drives such as flash-based solid state drives (SSDs) to act as a cache for one or more slower hard disk drives. The bcache-tools package contains the utilities for manipulating bcache

Testing covers not only bcache-tools but also the interaction between bcache-tools and other packages: kernel, util-linux and dracut.

Starting with a stable F20 system with /home on LVM on bcache, we can go forward and have / on bcache. Consider thought that bcache is EXPERIMENTAL!


This test requires the following test case as preparation: /home on bcache (no LVM)

The prerequisites for running the bcache-tools testcases can be found on this page


To get / on bcache we'll stop using /home on bcache first:

  1. Open terminal
  2. Switch to root user: su -
  3. if needed make a backup of /home on your root filesystem.
  4. comment /home out in your /etc/fstab
  5. unmount /home: umount /home
  6. if applicable restore your bachup to the /home directory

How to test

Now your /home is in your root filesystem. Next:

  1. create a new filesystem on /dev/bcache0: mkfs -t ext4 -L ROOTFS /dev/bcache0
  2. mount it: mount /dev/bcache0 /mnt
  3. copy your current root filesystem to /mnt: cp -ax / /mnt
  4. edit /mnt/fstab so your root fs is mounted like: LABEL=ROOTFS / ext4 defaults 1 1

Now we have a duplicate root filesystem on /dev/bcache0. To use it we need to build a new initramfs:

  1. rename your current initramfs: mv /boot/initramfs...img /boot/initramfs...img.sav
  2. build a new initramfs with dracut -N

Now reboot your system.

  1. while in grub replace the root=UUID=... parameter in the "linux" line by: root=LABEL=ROOTFS
  2. boot your system.

If all goes well, your system now boots fine and it's running on bcache!

  1. Edit your /etc/grub2.cfg file..
  2. .. duplicate the first "menuentry ... { ...}" (about 15 lines).
  3. Now change the first one and replace the root=UUID=... parameter in the "linux" line by root=LABEL=ROOTFS
  4. reboot again
  5. reboot your system to see if it boots OK.
  6. do some other testing if you like.

Expected Results

  1. All steps complete without errors