FortiWeb 6.2.4 disk sda1 i almost full.

Hi,

I have 2 FortiWeb machines on a Vmware environment.
Both are in HA.
Both have 2 sda and sdb drives.
The sda disk is 2GB
The sdb drive is 30GB
I can extend the sdb drive.

How to extend a sda drive which is 2GB and is 97% full.
There are "/data" files on / dev/sda1