Enterprise Volume Management System


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Converting To EVMS

  1. Why convert to EVMS?

    Everyone who has installed Linux is probably familiar with partitioning hard-drives, usually with a program like fdisk, cfdisk or Disk-Druid. Many people have also added software-RAID to their system using tools like mdadm or raidtools. Others use LVM tools as well to create volume groups and logical volumes. Finally, those partitions and volumes need filesystems on top of them in order to be useful, and there are four commonly used filesystems to choose from.

    This is a lot of different tools to learn just for managing your storage devices. Each tool has a different interface - some are purely command-line, some have interactive shells, some have ncurses-based UIs. Some tools have extra configuration files and all the tools have different options. In addition, using a combination of these tools may involve subtle ordering issues when it comes to booting your system or making changes to one aspect of your storage.

    The Enterprise Volume Management System (EVMS) allows you to do away with all of these different tools. It provides all your storage management needs in one easy-to-use interface. It automatically handles all of the ordering issues associated with getting your partitions and volumes running at boot-time, and with making configuration changes on your running system.

    If you're looking to for an easier solution for storage administration, we highly recommend converting to EVMS.

  2. Download the EVMS packages.

    The first step in converting to EVMS is to obtain all of the necessary packages. Please see the download section of the installation instructions for a list of all packages that are required for building and running EVMS.

  3. Compile the kernel.

    The next step is to patch, configure, and compile your kernel to support EVMS. The kernel section of the installation instructions will give you all the details about which patches to apply and which options to choose.

    If you are currently using LVM1, be sure to leave that option enabled in your kernel configuration, since you'll be booting this new kernel before you've fully converted to EVMS. The LVM1 and Device-Mapper drivers can co-exist in the same kernel without problems. After the conversion to EVMS is complete, you may go back and recompile your kernel again without LVM1 support.

    EVMS also uses the MD driver for performing software-RAID. If you are currently using raidtools or mdadm for software-RAID, you should simply keep the same kernel RAID options that you already have enabled.

    After compiling, reboot your machine using the new kernel.

  4. Compile the EVMS tools.

    After rebooting, the next step is to build and install EVMS. See the tools section of the installation instructions for details.

  5. Run the EVMS UI.

    Since you've already booted your Device-Mapper-enabled kernel, you can immediately start one of the EVMS user-interfaces. If you're running a graphical desktop, run evmsgui. If you're using a text terminal, run evmsn. The first screen you will see with either of these UIs is the Volumes panel. Explore all the panels in the UI to see how EVMS represents the various devices and volumes on your system.

    The most important thing to notice right now is the names that EVMS assigns to your existing volumes. Because your existing volumes are discovered as compatibility volumes, the names will be similar to what you've previously been using. All volume names begin with /dev/evms. Here are a few specific examples.

    • A simple disk partition called /dev/hda5 will appear in EVMS as /dev/evms/hda5.

    • A software-RAID device called /dev/md1 will appear in EVMS as /dev/evms/md/md1.

    • An LVM1 volume called /dev/my_group/my_volume will appear in EVMS as /dev/evms/lvm/my_group/my_volume.

  6. Update /etc/fstab to use EVMS volume names.

    To use your EVMS volumes, you must tell Linux to mount them instead of your existing partitions and volumes. The best way to do this is to edit your /etc/fstab file and change the device name for each entry to the corresponding EVMS volume names. For example, the following entry for an LVM volume:

    /dev/my_group/home_volume /home reiserfs defaults 1 2

    would change to:

    /dev/evms/lvm/my_group/home_volume /home reiserfs defaults 1 2

    With these changes, each time your system boots, your filesystems will be mounted using the EVMS volumes.

  7. Update the boot-scripts.

    As explained in the activating volumes section of the installation instructions, the command evms_activate must be run from your boot-scripts in order to activate your volumes so they can be mounted. In addition to this change, if you run software-RAID or LVM1 tools (e.g. raidstart, vgscan, or vgchange) during your boot-scripts, those commands should be removed or disabled.

  8. Update the bootloader.

    In order to mount your root filesystem using EVMS, you must install the EVMS init-ramdisk image and update your boot-loader configuration. Please see the boot-loader and root-filesystem sections of the installation instructions for the complete details.

  9. One more reboot.

    Now that all of these items have been configured, you just need to reboot your machine one more time. When it boots, the kernel will load the init-ramdisk, which will run the EVMS tools to activate your volumes and mount your root filesystem. Then your boot-scripts will run the EVMS tools once more to make sure your /dev/evms/ directory correctly reflects the current state of your volumes. Finally, the remaining EVMS volumes will be mounted as specified in your /etc/fstab file. Everything else on your system should start up as you would normally expect.