Tagoracle errors

ORA-00845: MEMORY_TARGET not supported on this system

Getting ORA-00845: MEMORY_TARGET not supported on this system, while trying to start a database.

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


This is a very common error which you might face while starting up your oracle database. This happens when your system is out of temporary storage. While starting up the database oracle uses /dev/shm to store temporary files but when it runs out of memory you get this error.

/dev/shm is also know as tmpfs i.e. temporary file system which keeps all the file system in virtual memory to speed up several processes.


Increase the size of /dev/shm

To check the size of /dev/shm
root@localhost# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda3 10G 4.4G 2.9G 61% /
tmpfs 504M 76K 504M 1% /dev/shm
/dev/sda1 194M 25M 160M 14% /boot

To increase the size
root@localhost# mount -o remount,size=3G /dev/shm
Verify the size
root@localhost# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda3 7.6G 4.4G 2.9G 61% /
tmpfs 3G 1007M 2.1G 33% /dev/shm
/dev/sda1 194M 25M 160M 14% /boot

To make permanent changes to your file system update your fstab
root@localhost# vi /etc/fstab
tmpfs /dev/shm tmpfs defaults,size=3G 0 0


Update the new fstab file
root@localhost# mount -a

ORA-01034: ORACLE Not Available

What to do when we get  errors  like ORA-01034: ORACLE not available ORA-27101: shared memory realm does not exist.


The ORA-01034 is  simple error, it means that your database is down!  Oracle oerr utility notes this about the ORA-01034 error:

ORA-01034: ORACLE not available


 Oracle was not started up. Possible causes include the following:

  • The SGA requires more space than was allocated for it.
  • The operating-system variable pointing to the instance is improperly defined.


Refer to accompanying messages for possible causes and correct the problem mentioned in the other messages. If Oracle has been initialized, then on some operating systems, verify that Oracle was linked correctly. See the platform specific Oracle documentation.

You may find that you are experiencing ORA-01034 when attempting to upgrade your Oracle database.ORA-01034 is thrown during the attempt to upgrade because there is an invalid entry in one of the following files:

  1. /etc/oratab
  2. /var/opt/oracle/oratab

The ORA-01034 is a result of a discrepancy between ORACLE_HOME andORACLE_SID

To resolve ORA-01034, be sure that the ORACLE_HOME and ORACLE_SIDproperly match within the files /etc/oratab or /var/opt/oracle/oratab .


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