To check the tablespace size in oracle

select

df.tablespace_name "Tablespace",

totalusedspace "Used MB",

(df.totalspace - tu.totalusedspace) "Free MB",

df.totalspace "Total MB",

 round(100 * ( (df.totalspace - tu.totalusedspace)/ df.totalspace)) "Pct. Free"

from

(select tablespace_name, round(sum(bytes) / 1048576) TotalSpace from           

 dba_data_files group by tablespace_name) df,

(select round(sum(bytes)/(1024*1024)) totalusedspace, tablespace_name from dba_segments group by tablespace_name) tu

where df.tablespace_name = tu.tablespace_name ;

To add space to the tablespace using ASM :

ASM:

 alter tablespace USTTAX_DATA add datafile '+PROD_RB_DATA' size 10G;

 alter tablespace UTT_M2_DATA add datafile '+PROD_RB_DATA' size 10G;

To add space to the tablespace using regular filesystem :

Non-ASM: