How many HDD vacant slot you have in your computer. You can add new HDD and copy full database ( like Sapdata1 - sapdata7) which is critical to new HDD with other name. for example you want to copy sapdta1 to new hdd. Create newsapdata1 and copy from sapdata1 after copied rename the sapdata1 to sapdata1_old and newsapdata to sapdata1.
After renaming you can use this space in other volume like sapdata2 to sapdata7. For this activity you have to contact you OS persion who is given hardware and os support to you.
You have not mentioned here what os your are using. If you are using windows then you can do yourself. If you are using other os pls mentioned df -k output so tha we can see and reply accordingly.