Moving most consuming directory to the separate disk

In my case, one directory is consuming most of disk space dedicated for the system.

Stop the service.

Rename directory

export src="/var/ossec"
mv ${src} ${src}.backup

Attach new disk

Configure LVM, mount disk to the location

Move files from backup to new destination

sudo rsync -avAXH --progress ${src}.backup ${src}

Once happy, remove source

rm -rf ${src}.backup