Root partition full and can't account for all 4GB

root@RIGHTSTER-NAS:~# ls -la /apps
total 4
drwxrwxrwx 1 root  root    94 Nov 25 10:27 .
drwxr-xr-x 1 root  root   314 Nov 10 16:02 ..
drwxr-xr-x 1 root  root    52 Oct  2 02:00 APPGENIE
dr-xr-xr-x 1 root  root     0 Sep 12  2013 DO_NOT_DELETE
drwxr-xr-x 1 admin admin 1290 Sep  1 12:26 .freeapps
drwxr-xr-t 1 root  root    16 Dec 20  2013 .readydlna
drwxr-xr-x 1 root  root   132 Sep 29 11:31 smbplus

root@RIGHTSTER-NAS:~# systemctl restart mysqld
Failed to issue method call: Unit mysqld.service failed to load: No such file or directory. See system logs and 'systemctl status mysqld.service' for details.

root@RIGHTSTER-NAS:~# du -csh /var/lib/*
30M     /var/lib/apt
20K     /var/lib/connman
0       /var/lib/dbus
14M     /var/lib/dpkg
0       /var/lib/ftp
0       /var/lib/initscripts
0       /var/lib/insserv
12M     /var/lib/ldap
0       /var/lib/libuuid
4.0K    /var/lib/mdadm
0       /var/lib/misc
726M    /var/lib/mysql
8.0K    /var/lib/nfs
0       /var/lib/nut
24K     /var/lib/pam
0       /var/lib/php5
4.0K    /var/lib/random-seed
4.0K    /var/lib/readyNASVault.version
2.7M    /var/lib/samba
0       /var/lib/slapd
0       /var/lib/snmp
0       /var/lib/sudo
0       /var/lib/systemd
148K    /var/lib/ucf
0       /var/lib/update-rc.d
0       /var/lib/urandom
783M    total