System volume 'root' usage is 81 %

root@xxxxxx:~# df -h
Filesystem Size Used Avail Use% Mounted on
rootfs 4.0G 3.0G 728M 81% /
tmpfs 10M 4.0K 10M 1% /dev
/dev/md0 4.0G 3.0G 728M 81% /
tmpfs 996M 48K 996M 1% /dev/shm
tmpfs 996M 7.1M 989M 1% /run
tmpfs 996M 0 996M 0% /sys/fs/cgroup
tmpfs 996M 24K 996M 1% /media
/dev/md127 5.5T 2.1T 3.4T 39% /data
/dev/md127 5.5T 2.1T 3.4T 39% /home
/dev/md127 5.5T 2.1T 3.4T 39% /apps
/dev/md127 5.5T 2.1T 3.4T 39% /var/ftp/a_Seed_Photos
/dev/md127 5.5T 2.1T 3.4T 39% /run/nfs4/home
/dev/sde1 1.9T 842G 1022G 46% /media/ESATA_HDD_1
/dev/sde1 1.9T 842G 1022G 46% /var/ftp/ESATA_HDD_1
/dev/sde1 1.9T 842G 1022G 46% /run/nfs4/media/ESATA_HDD_1
/dev/sdf1 2.8T 1.2T 1.6T 42% /media/USB_HDD_1
/dev/sdf1 2.8T 1.2T 1.6T 42% /var/ftp/USB_HDD_1
/dev/sdf1 2.8T 1.2T 1.6T 42% /run/nfs4/media/USB_HDD_1 

root@xxxxxx:~# du -csh /var/*
0 /var/agentx
59M /var/backups
107M /var/cache
41M /var/cores
2.0T /var/ftp
577M /var/lib
0 /var/local
4.0K /var/lock
428M /var/log
0 /var/mail
8.0K /var/netatalk
0 /var/opt
16K /var/readydrop
732K /var/readynasd
4.0K /var/run
8.0K /var/spool
0 /var/tmp
4.0K /var/www
2.0T total 

root@xxxxxx:~# cat /proc/mounts
rootfs / rootfs rw 0 0
tmpfs /dev tmpfs rw,noatime,nodiratime,size=10240k,mode=755 0 0
devpts /dev/pts devpts rw,noatime,nodiratime,mode=600 0 0
/dev/md0 / btrfs rw,noatime,nodiratime,nospace_cache 0 0
proc /proc proc rw,nosuid,nodev,noexec,noatime,nodiratime 0 0
sysfs /sys sysfs rw,nosuid,nodev,noexec,noatime,nodiratime 0 0
tmpfs /dev/shm tmpfs rw,nosuid,nodev 0 0
tmpfs /run tmpfs rw,nosuid,nodev,mode=755 0 0
tmpfs /sys/fs/cgroup tmpfs rw,nosuid,nodev,noexec,mode=755 0 0
cgroup /sys/fs/cgroup/systemd cgroup rw,nosuid,nodev,noexec,noatime,nodiratime,release_agent=/lib/systemd/systemd-cgroups-agent,name=s
ystemd 0 0
cgroup /sys/fs/cgroup/cpu cgroup rw,nosuid,nodev,noexec,noatime,nodiratime,cpu 0 0
cgroup /sys/fs/cgroup/blkio cgroup rw,nosuid,nodev,noexec,noatime,nodiratime,blkio 0 0
systemd-1 /proc/sys/fs/binfmt_misc autofs rw,noatime,nodiratime,fd=25,pgrp=1,timeout=300,minproto=5,maxproto=5,direct 0 0
debugfs /sys/kernel/debug debugfs rw,noatime,nodiratime 0 0
tmpfs /media tmpfs rw,nosuid,nodev,noexec,noatime,nodiratime,mode=755 0 0
fusectl /sys/fs/fuse/connections fusectl rw,noatime,nodiratime 0 0
configfs /sys/kernel/config configfs rw,noatime,nodiratime 0 0
/dev/md127 /data btrfs rw,noatime,nodiratime,nospace_cache 0 0
/dev/md127 /home btrfs rw,noatime,nodiratime,nospace_cache 0 0
/dev/md127 /apps btrfs rw,noatime,nodiratime,nospace_cache 0 0
/dev/md127 /var/ftp/a_Seed_Photos btrfs rw,noatime,nodiratime,nospace_cache 0 0
/dev/md127 /run/nfs4/home btrfs rw,noatime,nodiratime,nospace_cache 0 0
/dev/sde1 /media/ESATA_HDD_1 ufsd rw,noatime,nodiratime,nls=utf8,fmask=0,dmask=0 0 0
/dev/sde1 /var/ftp/ESATA_HDD_1 ufsd rw,noatime,nodiratime,nls=utf8,fmask=0,dmask=0 0 0
/dev/sde1 /run/nfs4/media/ESATA_HDD_1 ufsd rw,noatime,nodiratime,nls=utf8,fmask=0,dmask=0 0 0
/dev/sdf1 /media/USB_HDD_1 ufsd rw,noatime,nodiratime,nls=utf8,fmask=0,dmask=0 0 0
/dev/sdf1 /var/ftp/USB_HDD_1 ufsd rw,noatime,nodiratime,nls=utf8,fmask=0,dmask=0 0 0
/dev/sdf1 /run/nfs4/media/USB_HDD_1 ufsd rw,noatime,nodiratime,nls=utf8,fmask=0,dmask=0 0 0