/data is my big disk, /var/log is small. Could not resize LVM easily, so a temp solution.

mkdir /data/nagios/archives
mv /var/log/nagios/archives/* /data/nagios/archives
chown --reference /var/log/nagios/archives /data/nagios/archives
mount -o bind /data/nagios/archives/ /var/log/nagios/archives
grep archives /etc/mtab #select entry
cat >> /etc/fstab