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.
![[Note]](../images/note.png)
Note
Development versions of BLFS may not build or run
some packages properly if LFS or dependencies have been updated
since the most recent stable versions of the books.
Package Information
Download (HTTP): https://sourceware.org/ftp/lvm2/LVM2.2.03.23.tgz
Download MD5 sum: 0535b5e638b6f0b48f7b259e0ec0ba65
Download size: 2.7 MB
Estimated disk space required: 39 MB (add 20 MB for tests; transient files can grow up to around 300 MB in the /tmp directory during tests)
Estimated build time: 0.1 SBU (using parallelism=4; add 9 to 48 SBU for tests, depending on disk speed and whether ram block device is enabled in the kernel)
LVM2 Dependencies
Required
libaio-0.3.113
Optional
mdadm-4.2,
Valgrind-3.22.0,
Which-2.21,
xfsprogs-6.5.0 (all four may be used, but are not required,
for tests),
reiserfsprogs,
thin-provisioning-tools, and
vdo
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 --->
[*] 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
Install LVM2 by running the following
commands:
PATH+=:/usr/sbin \
./configure --prefix=/usr \
--enable-cmdlib \
--enable-pkgconfig \
--enable-udev_sync &&
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 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:
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 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 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
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
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.