Go to your linux source tree, and apply one of the pre-patches for MARS.
You can find them in the subdirectory pre-patches/ of the MARS sources.

These pre-patches are almost trivial, they contain only a few
EXPORT_SYMBOL() statements. Porting to other kernel versions should
be trivial. If not, please report a bug :)

One of the pre-patches has been ported to an openvz kernel
even by one of our sysadmins, who usually does no C programming.
So this should be no major hurdle.

Because of the need for some small pre-patches, there is currently
no infrastructure for builing MARS seaparately as standalone kernel module.
Currently, you have to compile it inplace in your kernel source tree.

Go to ${your_kernel_source}/block/ and clone the MARS git repository there.

Then build your kernel as usual.

In Kconfig, you will find lots of additional options for MARS. Most
of them should be left at their default. It suffices just to switch
on MARS as a whole, and let it build as a single kernel module.

Finally, copy userspace/marsadm to some appropriate location in
your $PATH.

Do the following at both your primary and secondary node:

After booting your pre-patched kernel, don't modprobe mars. Before
that, create an empty filesystem with at least 100GB (currently
ext3 recommended; there seem to remain some recursion deadlock problems
with xfs which will be hopefully fixed in the next time)
and mount it to /mars/ .

Additionally, you need an empty block device having exactly the same
size at both nodes. In the following, they are called /dev/vg-x/myspace .

On the primary:
	marsadm create-cluster

On the secondary:
	marsadm join-cluster ${hostname_of_primary}

Only after that, do on both nodes:
	modprobe mars

On the primary:
	marsadm create-resource myspace /dev/vg-x/myspace

Wait a few seconds until the state information about the new resource has
spread over the whole cluster.

On the secondary:
	marsadm join-resource myspace /dev/vg-x/myspace

Shortly after that, the initial full sync should start automatically.
On the primary, a device /dev/mars/myspace should appear, having exactly
the same size as /dev/vg-x/myspace .

Now you can use /dev/mars/myspace on the primary for creating a filesystem,
mounting, or exporting via iSCSI, etc.

From time to time, you should execute the following commands on one of
your nodes:
	marsadm log-rotate all
	sleep 10
	marsadm log-delete-all all
... in order to prevent your /mars/ filesystem from running full.

hint: use cron jobs for automation.

Most marsadm commands are very similar to drbdadm. A better documentation
should appear in the next months. The sourcecode of marsadm is a very
simple and stupid perl script, which intentionally does not use any
perl module and no OO. The source code will tell you almost anything
about the symlinks present in /mars/ until there is better documentation.

If you are curious about how MARS replicates its state information
over the network, just do the following on both nodes:
	watch ls -l /mars/resource-myspace/

Alternatively / additionally, you may try Joerg's script mars-status.pl
which will deliver colorful state reports from the practical viewpoint
of an experienced sysadmin.