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/LVM2.2.03.36.tgz
-
Download MD5 sum: 62a7c701fe07a5c30ff9fcb624cd3437
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Download size: 2.8 MB
-
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-6.17, dosfstools-4.2,
jfsutils-1.1.15, mdadm-4.4, parted-3.6, Valgrind-3.26.0, Which-2.23, xfsprogs-6.17.0,
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.
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
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 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
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
rm -fv /usr/lib/udev/rules.d/69-dm-lvm.rules
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.
rm
.../69-dm-lvm.rules: Under certain circumstances,
this udev rule calls systemd-run, which is not
available on sysv. It performs actions that are done by another
boot script anyway, so it is not needed.