Sergi Barroso wrote:

Today I started installation, and I founded my first problem, when 
installing openssi package it returns me this error:

Finding valid ramdisk creators.
Using mkinitrd to build the ramdisk.
ldd: /cluster/lib/cfstab: No existe el fichero o el directorio
mkinitrd failed to create initrd image.

cfstab left on this path, what's exactly in this file? A copy of fstab 
with clusterfs mount points?

cfstab is the table that shows which filesystem types should have cfs layered on top of them:
#<fstype>	<cluster>	<defaults>
ext2		cfs		
ext3		cfs			# for ext3 
gfs		parallel	
tmpfs		cfs			# for udev
(so we don't layer cfs on top of gfs, each node mounts it in parallel).

I've seen this problem before, I think it's because you've missed one of the steps in the installation.   You are following my "howto" document step by step?

Could you do:
$ dpkg -l initrd-tools
and send us the output.