Error: 1030 Got error 28 from storage engine SQL=SELECT

[Bobses]

Hello
I runned in this morning Backup from Panel sentora. After few hours I received the error from title.
I connected to server thru ssh:

Code:

df -h
Filesystem         Size  Used Avail Use% Mounted on
/dev/ploop36676p1   30G   28G   16M 100% /
none               512M  4.0K  512M   1% /dev
none               4.0K     0  4.0K   0% /sys/fs/cgroup
none               103M  1.1M  102M   2% /run
none               5.0M     0  5.0M   0% /run/lock
none               512M     0  512M   0% /run/shm
none               100M     0  100M   0% /run/user

Again:

Code:

sudo du -sh *
6.5M    bin
4.0K    boot
4.0K    dev
18G     etc
0       fastboot
32K     home
27M     lib
4.0K    lib64
16K     lost+found
4.0K    media
4.0K    mnt
4.0K    opt
du: cannot access 'proc/3849/task/3849/fd/4': No such file or directory
du: cannot access 'proc/3849/task/3849/fdinfo/4': No such file or directory
du: cannot access 'proc/3849/fd/4': No such file or directory
du: cannot access 'proc/3849/fdinfo/4': No such file or directory
0       proc
172K    root
1.1M    run
6.9M    sbin
12K     srv
0       sys
4.0K    tmp
661M    usr
9.8G    var

Another one:

Code:

cd /etc
/etc$ sudo du -sh *
4.0K    ODBCDataSources
........
18G     sentora
........

So, please help me: what is wrong here? How can I reduce this size?
Can you help me, please?
Thank you very much.