Building DRBD from source

Building DRBD from source
Prev	Chapter 4. Building and installing DRBD from source	Next

Checking build prerequisites

Before being able to build DRBD from source, your build host must fulfill the following prerequisites:

make, gcc, the glibc development libraries, and the flex scanner generator must be installed.

	Note
	You should make sure that the `gcc` you use to compile the module is the same which was used to build the kernel you are running. If you have multiple `gcc` versions available on your system, DRBD's build system includes a facility to select a specific `gcc` version.

For building directly from a git checkout, GNU Autoconf is also required. This requirement does not apply when building from a tarball.
If you are running a stock kernel supplied by your distribution, you should install a matching precompiled kernel headers package. These are typically named kernel-dev, kernel-headers, linux-headers or similar. In this case, you can skip the section called “Preparing the kernel source tree” and continue with the section called “Preparing the DRBD build tree”.

If you are not running a distribution stock kernel (i.e. your system runs on a kernel built from source with a custom configuration), your kernel source files must be installed. Your distribution may provide for this via its package installation mechanism; distribution packages for kernel sources are typically named kernel-source or similar.

	Note
	On RPM-based systems, these packages will be named similar to `kernel-source-version.rpm`, which is easily confused with `kernel-version.src.rpm`. The former is the correct package to install for building DRBD.

"Vanilla" kernel tarballs from the kernel.org archive are simply named linux-version-tar.bz2 and should be unpacked in /usr/src/linux-version, with the symlink /usr/src/linux pointing to that directory.

In this case of building DRBD against kernel sources (not headers), you must continue with the section called “Preparing the kernel source tree”.

Preparing the kernel source tree

To prepare your source tree for building DRBD, you must first enter the directory where your unpacked kernel sources are located. Typically this is /usr/src/linux-version, or simply a symbolic link named /usr/src/linux:

cd /usr/src/linux

The next step is recommended, though not strictly necessary. Be sure to copy your existing .config file to a safe location before performing it. This step essentially reverts your kernel source tree to its original state, removing any leftovers from an earlier build or configure run:

make mrproper

Now it is time to clone your currently running kernel configuration into the kernel source tree. There are a few possible options for doing this:

Many reasonably recent kernel builds export the currently-running configuration, in compressed form, via the /proc filesystem, enabling you to copy from there:
```
zcat /proc/config.gz > .config
```
SUSE kernel Makefiles include a cloneconfig target, so on those systems, you can issue:
```
make cloneconfig
```
Some installs put a copy of the kernel config into /boot, which allows you to do this:
```
cp /boot/config-`uname -r` .config
```
Finally, you may simply use a backup copy of a .config file which you know to have been used for building the currently-running kernel.

Preparing the DRBD build tree

Any DRBD compilation requires that you first configure your DRBD source tree with the included configure script.

Note

The information in this section applies to DRBD 8.3.6 and above. Up until release 8.3.5, DRBD had no configure script.

When building from a git checkout, the configure script does not yet exist. You must create it by simply typing autoconf at the top of the checkout.

Invoking the configure script with the --help option returns a full list of supported options. The table below summarizes the most important ones:

Table 4.1. Options supported by DRBD's configure script

Option	Description	Default	Remarks
`--prefix`	Installation directory prefix	`/usr/local`	This is the default to maintain Filesystem Hierarchy Standard compatibility for locally installed, unpackaged software. In packaging, this is typically overridden with `/usr`.
`--localstatedir`	Locate state directory	`/usr/local/var`	Even with a default `prefix`, most users will want to override this with `/var`.
`--sysconfdir`	System configuration directory	`/usr/local/etc`	Even with a default `prefix`, most users will want to override this with `/etc`.
`--with-km`	Build the DRBD kernel module	no	Enable this option when you are building a DRBD kernel module.
`--with-utils`	Build the DRBD userland utilities	yes	Disable this option when you are building a DRBD kernel module against a new kernel version, and not upgrading DRBD at the same time.
`--with-heartbeat`	Build DRBD Heartbeat integration	yes	You may disable this option unless you are planning to use DRBD's Heartbeat v1 resource agent or dopd.
`--with-pacemaker`	Build DRBD Pacemaker integration	yes	You may disable this option if you are not planning to use the Pacemaker cluster resource manager.
`--with-rgmanager`	Build DRBD Red Hat Cluster Suite integration	no	You should enable this option if you are planning to use DRBD with rgmanager, the Red Hat Cluster Suite cluster resource manager.
`--with-xen`	Build DRBD Xen integration	yes (on x86 architectures)	You may disable this option if you are not planning to use the `block-drbd` helper script for Xen integration.
`--with-bashcompletion`	Build programmable bash completion for drbdadm	yes	You may disable this option if you are using a shell other than bash, or if you do not want to utilize programmable completion for the drbdadm command.
`--enable-spec`	Create a distribution specific RPM spec file	no	For package builders only: you may use this option if you want to create an RPM spec file adapted to your distribution. See also the section called “Building a DRBD RPM package”.

The configure script will adapt your DRBD build to distribution specific needs. It does so by auto-detecting which distribution it is being invoked on, and setting defaults accordingly. When overriding defaults, do so with caution.

The configure script creates a log file, config.log, in the directory where it was invoked. When reporting build issues on the mailing list, it is usually wise to either attach a copy of that file to your email, or point others to a location from where it may be viewed or downloaded.

Building DRBD userspace utilities

	Important
	Building userspace utilities requires that you configured DRBD with the `--with-utils` option, which is enabled by default.

To build DRBD's userspace utilities, invoke the following commands from the top of your DRBD checkout or expanded tarball:

	$ make
	$ sudo make install

This will build the management utilities (drbdadm, drbdsetup, and drbdmeta), and install them in the appropriate locations. Based on the other --with options selected during the configure stage, it will also install scripts to integrate DRBD with other applications.

Compiling DRBD as a kernel module

	Important
	Building the DRBD kernel module requires that you configured DRBD with the `--with-km` option, which is disabled by default.

Building DRBD for the currently-running kernel

After changing into your unpacked DRBD sources directory, you should now change into the kernel module subdirectory, simply named drbd, and build the module there:

cd drbd
make clean all

This will build the DRBD kernel module to match your currently-running kernel, whose kernel source is expected to be accessible via the /lib/modules/`uname -r`/build symlink.

Building against precompiled kernel headers

If the /lib/modules/`uname -r`/build symlink does not exist, and you are building against a running stock kernel (one that was shipped pre-compiled with your distribution), you may also set the KDIR variable to point to the matching kernel headers (as opposed to kernel sources) directory. Note that besides the actual kernel headers — commonly found in /usr/src/linux-version/include — the DRBD build process also looks for the kernel Makefile and configuration file (.config), which pre-built kernel headers packages commonly include. To build against precompiled kernel headers, issue, for example:

$ cd drbd
$ make clean
$ make KDIR=/lib/modules/2.6.31/build

Building against a kernel source tree

If you are building DRBD against a kernel other than your currently running one, and you do not have precompiled kernel sources for your target kernel available, you need to build DRBD against a complete target kernel source tree. To do so, set the KDIR variable to point to the kernel sources directory:

$ cd drbd
$ make clean
$ make KDIR=/path/to/kernel/source

Using a non-default C compiler

You also have the option of setting the compiler explicitly via the CC variable. This is known to be necessary on some Fedora versions, for example:

cd drbd
make clean
make CC=gcc32

Checking for successful build completion

If the module build completes successfully, you should see a kernel module file named drbd.ko in the drbd directory. You may interrogate the newly-built module with /sbin/modinfo drbd.ko if you are so inclined.

Prev	Up	Next
Checking out sources from the public DRBD source repository	Home	Building a DRBD RPM package