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
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
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Download (HTTP): https://sourceware.org/ftp/lvm2/LVM2.2.03.23.tgz
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Download MD5 sum: 0535b5e638b6f0b48f7b259e0ec0ba65
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Download size: 2.7 MB
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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)
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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
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.