QA:Testcase bcache-tools root on bcache (LVM)

Description

This page describes a test case for bcache-tools: "/ on bcache using LVM"

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, dracut and lvm2.

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

Prerequisites

This test requires the following test case as preparation: /home on bcache (LVM)

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

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

Now we have a duplicate root filesystem on /dev/BCACHE/ROOTFS. 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: dracut -N

Now reboot your system.

1. while in grub replace the root=UUID=... parameter in the "linux" line by: root=LABEL=ROOTFS
2. remove any rd.lvm=0 occurrence
3. boot it.

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

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