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Revision as of 06:01, 12 October 2013 by Rolffokkens (talk | contribs)


Description

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, dracut and lvm2.

Once your fresh Fedora 20 system is running, we will "move" /home to a Logical Volume (LVM) on a bcache device. Because of the flexibility that LVM provides the approach is quite different from page 1.A, for example we'll start by using sda4!

Prerequisites

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

Setup

Do the following steps:

  1. Open terminal
  2. Switch to root user: su -
  3. Install bcache tools: yum install bcache-tools

How to test

Now create anb use the bcache devices:

  1. Make /dev/sda4 a bcache backing device: make-bcache -B /dev/sda4
  2. Make /dev/sdb1 a bcache caching device: make-bcache -C /dev/sdb1
  3. Note the set uuid and attach /dev/sdb1 to /dev/sda2: echo <set uuid> > /sys/block/bcache0/bcache/attach

Now you have a bcache device: /dev/bcache0

  1. use "bcache-status -s" to see details about your bcache device.
  2. create a Physical Volume: pvcreate /dev/bcache0
  3. create a Volume Group: vgcreate BCACHE /dev/bcache0
  4. create a Logical Volume: lvcreate -L 2G -n HOME BCACHE
  5. create a filesystem: mkfs -t ext4 -L HOME /dev/BCACHE/HOME

This will be our new /home device. To use it first move the current /home to another mount point:

  1. replace /home entry in your /etc/fstab: LABEL=HOME /home ext4 defaults 1 2
  2. commands step by step:
    1. mkdir /home.old
    2. umount /home
    3. mount /dev/sda2 /home.old
    4. mount /home
    5. cp -ax /home.old/* /home
    6. umount /home.old
  3. build a new initramfs with dracut -N

Now you have a system with /home on LVM2 on bcache.

  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