Archive for the ‘Oracle’ Category

Today I came into the error ORA-00845: MEMORY_TARGET not supported on this system when setting the parameter MEMORY_TARGET on an Oracle 11.2.0.1.0 instance.

SQL> alter system set memory_target=9G scope=spfile;

System altered.

SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup
ORA-00845: MEMORY_TARGET not supported on this system

The solution is to make sure that you have /dev/shm mounted under shmfs. The size should be greater or equal to the size you set MEMORY_TARGET to.

as root:
mount -t tmpfs shmfs -o size=9216m /dev/shm

SQL> startup
ORACLE instance started.

Total System Global Area 9620525056 bytes
Fixed Size 2215704 bytes
Variable Size 4966056168 bytes
Database Buffers 4630511616 bytes
Redo Buffers 21741568 bytes
Database mounted.
Database opened.

Make sure to make an entry in your /etc/fstab to make the changes persistent across reboots.
The entry should be like:
shmfs /dev/shm tmpfs size=9216m 0 0

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When installing Oracle 11gR2 (11.2.0.1) on Centos Linux 6.2 64-bit, the Oracle installer will fail the package verification for the x86 packages, even if the required packages have been installed. This is because the installer cannot verify the newer versions of the packages. You can safely ignore the errors and continue with the installation.

Configuring Oracle Enterprise Manager on Oracle 11g through command ’emctl -config dbcontrol db -repos create’ may sometimes lead to error ORA-01921

Go through the following steps to resolve this issue.

  1. In sqlplus :
    drop user sysman cascade;
    drop public synonym SETEMVIEWUSERCONTEXT;
    drop role MGMT_USER;
    drop PUBLIC SYNONYM MGMT_TARGET_BLACKOUTS;
    drop user MGMT_VIEW;
  2. emca -deconfig dbcontrol db
    emca -config dbcontrol db -repos create