6.2. Build the LVM 1 kernel module

6.2.1. Building a patch for your kernel

In order to patch the linux kernel to support LVM 1.0.8, you must do the following:

1. Unpack LVM 1.0.8

   # tar zxf lvm_1.0.8.tar.gz

2. Enter the root directory of that version.

   # cd LVM/1.0.8

3. Run configure

   # ./configure

   You will need to pass the option --with-kernel_dir to configure if your linux kernel source is not in /usr/src/linux. (Run ./configure --help to see all the options available)

4. Enter the PATCHES directory

   # cd PATCHES

5. Run 'make'

   # make

   You should now have a patch called lvm-1.0.8-$KERNELVERSION.patch in the patches directory. This is the LVM kernel patch referenced in later sections of the howto.

6. Patch the kernel

   # cd /usr/src/linux ; patch -pX < /directory/lvm-1.0.8-$KERNELVERSION.patch

6.2.2. Building the LVM module for Linux 2.2.17+

The 2.2 series kernel needs to be patched before you can start building, look elsewhere for instructions on how to patch your kernel.

Patches:

1. rawio patch

   Stephen Tweedie's raw_io patch which can be found at http://www.kernel.org/pub/linux/kernel/people/sct/raw-io

2. lvm patch

   The relevant LVM 1 patch which should be built out of the PATCHES sub-directory of the LVM distribution. More information can be found in Section 6.2.1, Building a patch for your kernel.

Once the patches have been correctly applied, you need to make sure that the module is actually built, LVM 1 lives under the block devices section of the kernel config, you should probably request that the LVM /proc information is compiled as well.

Build the kernel modules as usual.

6.2.3. Building the LVM modules for Linux 2.4

The 2.4 kernel comes with LVM 1 already included although you should check at the Sistina web site for updates, (eg. v2.4.9 kernels and earlier must have the latest LVM 1 patch applied ). When configuring your kernel look for LVM 1 under Multi-device support (RAID and LVM). LVM 1 can be compiled into the kernel or as a module. Build your kernel and modules and install then in the usual way. If you chose to build LVM as a module it will be called lvm-mod.o

If you want to use snapshots with ReiserFS, make sure you apply the linux-2.4.x-VFS-lock patch (there are copies of this in the LVM/1.0.8/PATCHES directory.)

6.2.4. Checking the proc file system

If your kernel was compiled with the /proc file system (most are) then you can verify that LVM is present by looking for a /proc/lvm directory. If this doesn't exist then you may have to load the module with the command

 # modprobe lvm-mod 
         

If /proc/lvm still does not exist then check your kernel configuration carefully.

When LVM is active you will see entries in /proc/lvm for all your physical volumes, volume groups and logical volumes. In addition there is a "file" called /proc/lvm/global which gives a summary of the LVM status and also shows just which version of the LVM kernel you are using.