If anyone is interested, this is how I did it without shutting down the server. And it worked.
#Add 2 30GB disk (sdb1=DB | sdc1=rrd)
#Rescan to find HDD - without shutdown echo "- - -" > /sys/class/scsi_host/host2/scan #check if it got added fdisk -l ls -la /dev/sd*
#Stop daemons service crond stop service snmpd stop service syslog-ng stop service httpd stop service auditd stop #Stop sql last service mysqld stop
#Configure DB HDD fdisk /dev/sdb n p 1 <cr> <cr> w #Configure rrd HDD fdisk /dev/sdc n p 1 <cr> <cr> w
#Format them in ext4 mkfs.ext4 /dev/sdb1 mkfs.ext4 /dev/sdc1
#Rename DB folder cd /var/lib/ mv mysql mysql_tmp #Recreate mysql folder mkdir mysql #Mount the DB hard drive mount -t ext4 /dev/sdb1 /var/lib/mysql #Copy files over and preserve owners/perms cp -rp mysql_tmp/* mysql/ #change owner/perms of mysql folder chown mysql:mysql mysql
#Rename rrd folder cd /opt/observium mv rrd rrd_tmp #Recreate rrd folder mkdir rrd #Mount the rrd hard drive mount -t ext4 /dev/sdc1 /opt/observium/rrd #Copy files over and preserve owners/perms cp -rp rrd_tmp/* rrd/ #change owner/perms of mysql folder chown apache:apache rrd
#mount at startup - edit /etc/fstab /dev/sdb1 /var/lib/mysql ext4 defaults 0 0 /dev/sdc1 /opt/observium/rrd ext4 defaults 0 0
#Start daemons service mysqld start
service httpd start service syslog-ng start service snmpd start service crond start service auditd start