Where is the space on /var being used

I'm a novice linux admin and now responsible for the OS of a 3 node Tomcat cluster.
(Tomcat is handled by the DEVs luckily.)

I got alarmed by our monitoring solution that /var on server01 has only 172MB left of free space.
Most likely because /var/log did fill up.

So I investigated with:

server01:/var# for i in $(ls); do du -sh $i; done
3.5M backups
100M cache
51M lib
0   local
0   lock
598M log
0   mail
0   opt
40K run
32K spool
144K tmp
4.0K www

If I sum that up I end by something around 760MB used.
The numbers don't change if I dig deeper into the directory tree. So this is correct.

But if I execute a df -h I end up with completely different numbers for /var.
df shows that 2.8G out of 3.0G are used.

server01:/var# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda1             950M  205M  697M  23% /
tmpfs                 2.0G     0  2.0G   0% /lib/init/rw
udev                  2.0G  4.0K  2.0G   1% /dev
/dev/sda3             961M   33M  928M   4% /tmp
/dev/dm-0             2.0G  506M  1.5G  26% /usr
/dev/dm-1             3.0G  2.8G  172M  95% /var
/dev/dm-2              20G   17G  3.3G  84% /home

The funny thing is, that the other 2 nodes are reporting even more used spaced on /var.
Because /var/log/ on node 2 and 3 are consuming 200-300MB more space.
But partitions and the underlying LVM are having the same size on all 3 nodes.

On server02 and server03 df -h reports that everything is fine and only 1.0 to 1.2GB are used from 3.0GB.

So where is my space being used?

I heared of those little bastards called inodes and checked for this.
df -i reports:

server01:/var# df -i
Filesystem            Inodes   IUsed   IFree IUse% Mounted on
/dev/sda1             123648    6099  117549    5% /
tmpfs                 506908       3  506905    1% /lib/init/rw
udev                  506487     675  505812    1% /dev
/dev/sda3             987968       7  987961    1% /tmp
/dev/dm-0            2048000   19786 2028214    1% /usr
/dev/dm-1             705808    1807  704001    1% /var
/dev/dm-2            13619632    5906 13613726    1% /home

And on server02 and server03:

server03:/var# df -i
Filesystem            Inodes   IUsed   IFree IUse% Mounted on
/dev/sda1             123648    6100  117548    5% /
tmpfs                 506908       3  506905    1% /lib/init/rw
/dev                  506487     675  505812    1% /dev
/dev/sda3             987968       7  987961    1% /tmp
/dev/dm-0            2048000   19784 2028216    1% /usr
/dev/dm-1            3096576    1758 3094818    1% /var
/dev/dm-2            13113840    5642 13108198    1% /home

So /var on server01 has 705.808 inodes, while server02 and server03 have 3.096.576 inodes on /var.
But is this really the cause? As only 1% is used on each node.

If yes, how do I increase the inodes?
(All filesystems are XFS out of / that is ext2)

/etc/fstab is the same on all 3 nodes.
OS is Debian Lenny 64bit with Kernel 2.6.35.4.

Regards