CP : error writing '/var/www and No space left on device

I tried to copy all files in 1 folder
first it was permission denied
then I run this command
chattr -i /var/www/clients/client1/web1
then

Code:

 cp backup.zip /var/www/www.example.com

show this error

Any idea? did I missed something? because I didn't add partition mount in etc/fstab during ispconfig installation in Installing PureFTD and Quota.

Code:

root@nursingcpdunits:~# df -h
Filesystem      Size  Used Avail Use% Mounted on
udev            2.0G     0  2.0G   0% /dev
tmpfs           396M   41M  355M  11% /run
/dev/vda1        60G   60G     0 100% /
tmpfs           2.0G     0  2.0G   0% /dev/shm
tmpfs           5.0M  4.0K  5.0M   1% /run/lock
tmpfs           2.0G     0  2.0G   0% /sys/fs/cgroup
tmpfs           396M     0  396M   0% /run/user/0

 

Then I've got error of my website

 

The root partition is full. The / or
/dev/vda1 is 100 % full. Is that
backup.zip very big? Remove one
Copy to free disk space.
By the way, why do the files have
The immutable attribute?

 

Yeah I delete some non useful file. to open up more space. any suggestion of VPS have much SSD.