Database not start due to memory_target is higher than machine memory

When i try to startup i found this error:

[oracle@wcp12cr2 ~]$ sqlplus "/ as sysdba"

SQL*Plus: Release 12.1.0.1.0 Production on Tue Sep 19 23:31:42 2017

Copyright (c) 1982, 2013, Oracle.  All rights reserved.

Connected to an idle instance.

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

this is due to memory target parameter is higher than memory machine, so to startup this database we are going to initiate it with a new init.ora, because direct modifications with any text editor in spfileorcl.ora is not possible (file will become corrupt)

[oracle@wcp12cr2 dbs]$ cd $ORACLE_HOME/dbs
[oracle@wcp12cr2 dbs]$ ls -ltr
total 32
-rw-r--r--. 1 oracle oinstall 2992 Feb  3  2012 init.ora
-rw-r-----. 1 oracle oinstall   24 Nov 11  2015 lkORCL
-rw-r-----. 1 oracle oinstall 7680 Nov 11  2015 orapworcl
-rw-rw----. 1 oracle oinstall 1544 Sep 19 23:41 hc_orcl.dat
-rw-r-----. 1 oracle oinstall 2560 Sep 19 23:42 spfileorcl.ora

[oracle@wcp12cr2 dbs]$ cat spfileorcl.ora
C"▒▒Vt5CC"Vxorcl.__data_transfer_cache_size=0
orcl.__db_cache_size=2147483648
orcl.__java_pool_size=16777216
orcl.__large_pool_size=33554432
orcl.__oracle_base='/oracle/db'#ORACLE_BASE set from environment
orcl.__pga_aggregate_target=1979711488
orcl.__sga_target=2952790016
orcl.__shared_io_pool_size=150994944
orcl.__shared_pool_size=570425344
orcl.__streams_pool_size=0
*.audit_file_dest='/oracle/db/admin/orcl/adump'
*.audit_trail='db'
*.compatible='12.1.0.0.0'
*.control_files='/oracle/db/oradataCC"F/orcl/control01.ctl','/oracle/db/fast_recovery_area/orcl/control02.ctl'
*.db_block_size=8192
*.db_domain=''
*.db_name='orcl'
*.db_recovery_file_dest='/oracle/db/fast_recovery_area'
*.db_recovery_file_dest_size=4800m
*.diagnostic_dest='/oracle/db'
*.dispatchers='(PROTOCOL=TCP) (SERVICE=orclXDB)'
*.memory_target=4703m
*.open_cursors=300
*.processes=300
*.remote_login_passwordfile='EXCLUSIVE'
*.undo_tablespace='UNDOTBS1'
 

if we look for memory_target parameter in the above spfileorcl.ora we can see it is set to 4703m, which is greater than 4000m that my virtual machine has. I´m going to create a initorcl.ora file setting this parameter to 1024m as you can see below:

[oracle@wcp12cr2 dbs]$ cat initorcl.ora
*.audit_file_dest='/oracle/db/admin/orcl/adump'
*.audit_trail='db'
*.compatible='12.1.0.0.0'
*.control_files='/oracle/db/oradata/orcl/control01.ctl','/oracle/db/fast_recovery_area/orcl/control02.ctl'
*.db_block_size=8192
*.db_domain=''
*.db_name='orcl'
*.db_recovery_file_dest='/oracle/db/fast_recovery_area'
*.db_recovery_file_dest_size=4800m
*.diagnostic_dest='/oracle/db'
*.dispatchers='(PROTOCOL=TCP) (SERVICE=orclXDB)'
*.memory_target=1024m
*.open_cursors=300
*.processes=300
*.remote_login_passwordfile='EXCLUSIVE'
*.undo_tablespace='UNDOTBS1'

So, now i can backup existing spfileorcl.ora to spfileorcl.ora.bck and delete spfileorcl.ora in order database do not detect that file:

[oracle@wcp12cr2 dbs]$ cp spfileorcl.ora spfileorcl.ora.bck
[oracle@wcp12cr2 dbs]$ rm spfileorcl.ora

At this point, we are ready to startup database with startup pfile=/oracle/db/ohome/dbs/initorcl.ora:

[oracle@wcp12cr2 dbs]$ sqlplus " / as sysdba "

SQL*Plus: Release 12.1.0.1.0 Production on Tue Sep 19 23:36:46 2017

Copyright (c) 1982, 2013, Oracle.  All rights reserved.


Connected to:
Oracle Database 12c Enterprise Edition Release 12.1.0.1.0 - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options

SQL> startup pfile=/oracle/db/ohome/dbs/initorcl.ora
ORACLE instance started.

Total System Global Area 1068937216 bytes
Fixed Size                  2296576 bytes
Variable Size             713032960 bytes
Database Buffers          348127232 bytes
Redo Buffers                5480448 bytes
Database mounted.
Database opened.

And as we can see, we are using a pfile parameter:

SQL> show parameter spfile

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
spfile                               string
SQL> shutdown immediate;

Now, we can create a new spfile with right parameters:

SQL> create spfile from pfile;

File created.

And now, we can see that a new spfileorcl.ora is generated:

SQL> exit
Disconnected from Oracle Database 12c Enterprise Edition Release 12.1.0.1.0 - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options
[oracle@wcp12cr2 dbs]$ ls -ltr $ORACLE_HOME/dbs
total 28
-rw-r--r--. 1 oracle oinstall 2992 Feb  3  2012 init.ora
-rw-r-----. 1 oracle oinstall   24 Nov 11  2015 lkORCL
-rw-r-----. 1 oracle oinstall 7680 Nov 11  2015 orapworcl
-rw-r--r--. 1 oracle oinstall  550 Sep 19 23:36 initorcl.ora
-rw-rw----. 1 oracle oinstall 1544 Sep 19 23:41 hc_orcl.dat
-rw-r-----. 1 oracle oinstall 2560 Sep 20 00:00 spfileorcl.ora

So the last step is to restart database in order to start use spfileorcl.ora parameter file

SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup;
ORACLE instance started.

Total System Global Area 1068937216 bytes
Fixed Size                  2296576 bytes
Variable Size             713032960 bytes
Database Buffers          348127232 bytes
Redo Buffers                5480448 bytes
Database mounted.
Database opened.
SQL> show parameter pfile;

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
spfile                               string      /oracle/db/ohome/dbs/spfileorc
                                                 l.ora