LVM2-2.03.05

#### Beyond Linux® From Scratch (systemd Edition) - Version 9.0

### Chapter 5. File Systems and Disk Management

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# LVM2-2.03.05

## Introduction to LVM2

The LVM2 package is a set of tools that manage logical partitions. It allows spanning of file systems across multiple physical disks and disk partitions and provides for dynamic growing or shrinking of logical partitions, mirroring and low storage footprint snapshots.

This package is known to build and work properly using an LFS-9.0 platform.

### Package Information

- Download (HTTP): https://sourceware.org/ftp/lvm2/LVM2.2.03.05.tgz

- Download (FTP): ftp://sourceware.org/pub/lvm2/LVM2.2.03.05.tgz

- Download MD5 sum: 22e4a9e66b94bbfcf81444472ed32a2d

- Download size: 2.3 MB

- Estimated disk space required: 41 MB (add at least 594 MB for tests in the /tmp directory; additionally transient files can grow up to around 500 MB)

- Estimated build time: 0.2 SBU (using parallelism=4; add 15 SBU for tests)

### LVM2 Dependencies

#### Required

libaio-0.3.112

#### Optional

mdadm-4.0, reiserfsprogs-3.6.27, Valgrind-3.15.0, Which-2.21, xfsprogs-5.2.1 (all five may be used, but are not required, for tests), and thin-provisioning-tools

User Notes: http://wiki.linuxfromscratch.org/blfs/wiki/lvm2

## Kernel Configuration

Enable the following options in the kernel configuration and recompile the kernel:

### Note

There are several other Device Mapper options in the kernel beyond those listed below. In order to get reasonable results if running the regression tests, all must be enabled either internally or as a module. The tests will all time out if Magic SysRq key is not enabled.

    Device Drivers --->
      [*] Multiple devices driver support (RAID and LVM) ---> [CONFIG_MD]
        <*/M>   Device mapper support                         [CONFIG_BLK_DEV_DM]
        <*/M/ >   Crypt target support                        [CONFIG_DM_CRYPT]
        <*/M/ >   Snapshot target                             [CONFIG_DM_SNAPSHOT]
        <*/M/ >   Thin provisioning target                    [CONFIG_DM_THIN_PROVISIONING]
        <*/M/ >   Mirror target                               [CONFIG_DM_MIRROR]
    Kernel hacking --->
      [*] Magic SysRq key                                     [CONFIG_MAGIC_SYSRQ]

## Installation of LVM2

Install LVM2 by running the following commands:

    SAVEPATH=$PATH                  &&
    PATH=$PATH:/sbin:/usr/sbin      &&
    ./configure --prefix=/usr       \
                --exec-prefix=      \
                --enable-cmdlib     \
                --enable-pkgconfig  \
                --enable-udev_sync  &&
    make                            &&
    PATH=$SAVEPATH                  &&
    unset SAVEPATH

The tests use udev for logical volume synchronization, so the LVM udev rules and some utilities need to be installed before running the tests. If you are installing LVM2 for the first time, and do not want to install the full package before running the tests, the minimal set of utilities can be installed by running the following instructions as the `root` user:

    make -C tools install_tools_dynamic &&
    make -C udev  install                 &&
    make -C libdm install

To test the results, issue, as the `root` user:

    make check_local

Other targets are available and can be listed with make -C test help. The test timings are very dependent on the speed of the disk(s), and on the number of enabled kernel options.

The tests do not implement the “expected fail” possibility, and a small number of test failures is expected by upstream. More failures may happen because some kernel options are missing. For example, the lack of the dm-delay device mapper target may explain some failures. Some tests are flagged “warned” if thin-provisioning-tools are not installed. A workaround is to add the following flags to configure:

         --with-thin-check=    \
         --with-thin-dump=     \
         --with-thin-repair=   \
         --with-thin-restore=  \
         --with-cache-check=   \
         --with-cache-dump=    \
         --with-cache-repair=  \
         --with-cache-restore= \

Some tests may hang. They can be removed if necessary, for example: rm test/shell/lvconvert-raid-reshape.sh. The tests generate a lot of kernel messages, which may clutter your terminal. You can disable them by issuing dmesg -D before running the tests (do not forget to issue dmesg -E when tests are done).

### Note

The checks create device nodes in the /tmp directory. The tests will fail if /tmp is mounted with the nodev option.

Now, as the `root` user:

    make install

## Command Explanations

PATH=$PATH:/sbin:/usr/sbin: The path must contain `/sbin` and `/usr/sbin` for proper system tool detection by the configure script. This instruction ensures that PATH is properly set even if you build as an unprivileged user.

`--enable-cmdlib`: This switch enables building of the shared command library. It is required when building the event daemon.

`--enable-pkgconfig`: This switch enables installation of pkg-config support files.

`--enable-udev_sync`: This switch enables synchronisation with Udev processing.

`--enable-dmeventd`: This switch enables building of the Device Mapper event daemon.

## Contents

Installed Programs: blkdeactivate, dmeventd (optional), dmsetup, fsadm, lvm, and lvmdump. There are also numerous symbolic links to lvm that implement specific functionalities
Installed Libraries: libdevmapper.so and liblvm2cmd.so; optional: libdevmapper-event.so, libdevmapper-event-lvm2.so, libdevmapper-event-lvm2mirror.so, libdevmapper-event-lvm2snapshot.so, libdevmapper-event-lvm2raid.so, and libdevmapper-event-lvm2thin.so
Installed Directories: /etc/lvm and /lib/device-mapper (optional)

### Short Descriptions

blkdeactivate | is a utility to deactivate block devices.
dmeventd | (optional) is the Device Mapper event daemon.
dmsetup | is a low level logical volume management tool.
fsadm | is a utility used to resize or check filesystem on a device.
lvm | provides the command-line tools for LVM2. Commands are implemented via sympolic links to this program to manage physical devices (pv*), volume groups (vg*) and logical volumes (lv*).
lvmdump | is a tool used to dump various information concerning LVM2.
vgimportclone | is used to import a duplicated VG (e.g. hardware snapshot).
`libdevmapper.so` | contains the Device Mapper API functions.

Last updated on 2019-08-18 18:01:59 -0700

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