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Revision as of 17:29, 10 October 2013 by Rolffokkens (talk | contribs)


Description

/ on bcache (LVM)

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

Setup

To get / on bcache:

  1. create a Logical Volume: lvcreate -L 2G -n ROOTFS BCACHE
  2. create a filesystem: mkfs -t ext4 -L ROOTFS /dev/BCACHE/ROOTFS
  3. mount it: mount /dev/BCACHE/ROOTFS /mnt
  4. copy your current root filesystem to /mnt: cp -ax / /mnt
  5. edit /mnt/fstab so your root fs is mounted like: LABEL=ROOTFS / ext4 defaults 1 1


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

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

How to test

  1. reboot your system to see if it boots OK.
  2. do some other testing if you like.

Expected Results

  1. All steps complete without errors




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

To get / on bcache:

  • create a Logical Volume: lvcreate -L 2G -n ROOTFS BCACHE
  • create a filesystem: mkfs -t ext4 -L ROOTFS /dev/BCACHE/ROOTFS
  • mount it: mount /dev/BCACHE/ROOTFS /mnt
  • copy your current root filesystem to /mnt: cp -ax / /mnt
  • 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/BCACHE/ROOTFS. To use it we need to build a new initramfs:

  • rename your current initramfs: mv /boot/initramfs...img /boot/initramfs...img.sav
  • create a new initramfs: dracut -N

Now reboot your system. Edit your default grub entry:

  • replace the root=UUID=... parameter in the "linux" line by: root=LABEL=ROOTFS
  • remove any rd.lvm=0 occurrence
  • boot it.

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

  • Edit your /etc/grub2.cfg file..
  • .. duplicate the first "menuentry ... { ...}" (about 15 lines).
  • Now change the first one and replace the root=UUID=... parameter in the "linux" line by root=LABEL=ROOTFS
  • reboot again

Now your system should boot fine.