Zirconium Linux From Scratch - Version r12.4-45-systemd

Chapter 9. Grub Uefi Programs

LVM2-2.03.36

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.

Package Information

  • Download (HTTP): https://sourceware.org/ftp/lvm2/LVM2.2.03.36.tgz

  • Download SHA256 Sum: 44db12df4b990ed2c910176279f70b257f79ee6fc7684c577afbf59c13cd2cca

  • Download MD5 sum: 62a7c701fe07a5c30ff9fcb624cd3437

  • Download size: 2,949 KB

  • Estimated disk space required: 39 MB (add up to 300 MB for transient files for tests in the /tmp directory)

  • Estimated build time: 0.4 SBU (add 9 to 48 SBU for tests, depending on disk speed and options enabled in the kernel)

LVM2 Dependencies

Required

libaio-0.3.113

Optional for tests

'btrfs-progs', dosfstools-4.2, 'jfsutils', 'mdadm', 'parted', 'valgrind', Which-2.23, 'xfsprogs', reiserfsprogs, thin-provisioning-tools, and vdo

Kernel Configuration

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

[Note]

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.

In addition most of the optional packages for tests require kernel options that are needed. If the optional packages or their kernel options are not installed the tests will be flagged as either failed or skipped in an inconsistent way. 

Device Drivers --->
  [*] Block devices --->                                               [BLK_DEV]
    <*/M> RAM block device support                                 [BLK_DEV_RAM]
  [*] Multiple devices driver support (RAID and LVM) --->                   [MD]
    <*/M> Device mapper support                                     [BLK_DEV_DM]
    <*/M>   Crypt target support                                      [DM_CRYPT]
    <*/M>   Snapshot target                                        [DM_SNAPSHOT]
    <*/M>   Thin provisioning target                      [DM_THIN_PROVISIONING]
    <*/M>   Cache target (EXPERIMENTAL)                               [DM_CACHE]
    <*/M>   Mirror target                                            [DM_MIRROR]
    <*/M>   Zero target                                                [DM_ZERO]
    <*/M>   I/O delaying target                                       [DM_DELAY]

Kernel hacking --->
  Generic Kernel Debugging Instruments --->
    [*] Magic SysRq key                                            [MAGIC_SYSRQ]

Installation of LVM2

Configure LVM2 by running the following commands: 

PATH+=:/usr/sbin                \
./configure --prefix=/usr       \
            --enable-cmdlib     \
            --enable-pkgconfig  \
            --enable-udev_sync

Build LVM2 by running the following commands: 

make

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 commands: 

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

To test the results, issue: 

LC_ALL=en_US.UTF-8 make check_local

Some tests may hang. In this case they can be skipped by adding S=<testname> to the make command. 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 some test failures are expected by upstream.

  • Most tests will fail if the kernel does not have all the device drivers listed above.

  • More failures may happen because some kernel options are missing. For example, the lack of the dm-delay device mapper target explains some failures.

  • Some tests may fail if there is insufficient free space available in the partition with the /tmp directory. At least one test fails if 16 TB is not available.

  • 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]

Note

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

Now, Istall LVM2 by running the following commands: 

make install
make install_systemd_units

Command Explanations

PATH+=:/usr/sbin: The path must contain /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.

make install_systemd_units: This is needed to install a unit that activates logical volumes at boot. It is not installed by default.

Configuring LVM2

Config File

/etc/lvm/lvm.conf

Configuration Information

The default configuration still references the obsolete /var/lock directory. This creates a deadlock at boot time. Change this (as the root user): 

sed -e '/locking_dir =/{s/#//;s/var/run/}' \
    -i /etc/lvm/lvm.conf

Contents

Installed Programs: blkdeactivate, dmeventd (optional), dmsetup, fsadm, lvm, lvmdump, and lvm_import_vdo. 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-lvm2raid.so, libdevmapper-event-lvm2snapshot.so, libdevmapper-event-lvm2thin.so, and libdevmapper-event-lvm2vdo.so
Installed Directories: /etc/lvm and /usr/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 symbolic 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