Today We can discuss about the major oracle error , when we start the oracle database by issuing "Startup " commands its throw error ORA-00845: MEMORY_TARGET not supported on this system from the leaning stage its big hectic of us ,Here i Mentioned two methods to solve this error

Method 1:

SQL> startup 
ORA-00845: MEMORY_TARGET not supported on this system 

SQL> create pfile from spfile; file has been created

  we need the pfile to solve these error ,so let's create the pfile (The default file has been created on "$ORACLE_HOME/dbs/" location initdbname.ora)

SQL> shut immediate
oracle@host.] cd $ORACLE_HOME/dbs 
oracle@host dbs]ls 
spfileram.ora initram.ora

  now i m going to edit this pfile

oracle@host dbs]vi initram.ora

  now the parameters of pfile will be dispalyed here we should replace instead of MEMORY_TARGET into SGA_TARGET then press ESC :wq The File has been saved and then start your db using pfile

SQL> startup pfile='/u01/app/oracle/product/'

  Now the database is started