April 24, 2010


Filed under: ORA-00845, oracle — rmoff @ 17:57

This is a note-to-self really. When playing around with Oracle and something’s not working – RTFAL: Read The Flippin Alert Log!

After resizing a VM I was getting this problem:

[oracle@RNMVM01 ~]$ sqlplus / as sysdba

SQL*Plus: Release Production on Sat Apr 24 17:44:44 2010

Copyright (c) 1982, 2009, Oracle.  All rights reserved.

Connected to an idle instance.

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

I spent longer than I should have reading around on google, hitting various pages which all talked around memory management and /dev/shm

If I’d followed the logical process, I’d have checked the alert log:

Starting ORACLE instance (normal)
WARNING: You are trying to use the MEMORY_TARGET feature. This feature requires the /dev/shm file system to be mounted for at least 536870912 bytes. /dev/shm is either not mounted or is mounted with available space less than this size. Please fix this so that MEMORY_TARGET can work as expected. Current available is 529969152 and used is 0 bytes. Ensure that the mount point is /dev/shm for this directory.
memory_target needs larger /dev/shm

Following the syntax from here I duly allocated the space as Oracle requested:

[root@RNMVM01 ~]# mount -t tmpfs shmfs -o size=536870912 /dev/shm

and now Oracle was happy:

SQL> startup nomount
ORACLE instance started.

Total System Global Area  535662592 bytes
Fixed Size                  1337720 bytes
Variable Size             402654856 bytes
Database Buffers          125829120 bytes
Redo Buffers                5840896 bytes

As a ‘hack’ when it comes to Oracle server stuff, I have to say it’s a pleasure to work with most of the time, lots of helpful logs & documentation 🙂


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