rest disk space is decreasing every time i turn on ubuntu in vmware

rest disk space is decreasing every time i turn on ubuntu in vmware

i use vmware-toolbox-cmd disk shrink

it return error after running to around 50%

Filesystem Size Used Avail Use% Mounted on
/dev/sda1 29G 27G 819M 98% /
none 4.0K 0 4.0K 0% /sys/fs/cgroup
udev 492M 4.0K 492M 1% /dev
tmpfs 101M 1.1M 100M 2% /run
none 5.0M 0 5.0M 0% /run/lock
none 501M 152K 501M 1% /run/shm
none 100M 40K 100M 1% /run/user