How to resolve ORA-00845 errors in Oracle 11g

ORACLE11G database, modified memory parameter memory_max_target=943718400, turn off the error when the database restarts

[Oracle@instuctor shm]$ Sqlplus/as SYSDBA

Sql*plus:release 11.2.0.3.0 Production on Mon Nov 19 09:34:11 2012

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

Connected to a idle instance.

Sql> Startup

Ora-00845:memory_target not supported on this system

Sql> exit

Disconnected

[Oracle@instuctor shm]$ oerr ora 00845

00845, 00000, "Memory_target not supported on this system"

*cause:the memory_target parameter is not supported on this operating system OR/DEV/SHM is not sized correctly on L Inux.

*action:refer to documentation for a list of supported operating systems. Or, Size/dev/shm to is at least the sga_max_size in each

Oracle instance running on the system.

Look at the warning log for the database and see similar error messages

See more highlights of this column: http://www.bianceng.cnhttp://www.bianceng.cn/database/Oracle/

Mon Nov 19 09:34:14 2012

Starting ORACLE instance (normal)

Warning:you are trying to use the Memory_target feature. This feature requires THE/DEV/SHM file system to is mounted for at least 943718400

bytes. /DEV/SHM is either not mounted or are mounted with available spaces less than this size. Please fix the so memory_target can work

As expected. The current available are 845021184 and used is 208900096 bytes. Ensure that "mount point" Is/dev/shm for this directory.

Memory_target needs LARGER/DEV/SHM

Through the analysis of the above reasons, it seems that the remaining space of/DEV/SHM is too small.

[Oracle@instuctor shm]$ Df-h

FileSystem Size Used Avail use% mounted on

/DEV/SDA1 17G 15G 1.2G 93%/

Tmpfs 1.1G 209M 846M 20%/DEV/SHM

[Oracle@instuctor shm]$

Oracle is described in Metalink documentation: DOC id:note:460506.1.

There are only two ways to solve this problem,

1. Modify initialization parameters so that the setting of SGA in initialization parameters is less than/DEV/SHM size

2. Adjust the size of the/DEV/SHM.

Modifying the size of the/DEV/SHM can be accomplished by modifying the/etc/fstab:

[Root@instuctor ~]# Vi/etc/fstab

label=//ext3 Defaults 1 1

Tmpfs/dev/shm Tmpfs defaults,size=2g 0 0

Devpts/dev/pts devpts gid=5,mode=620 0 0

Sysfs/sys Sysfs Defaults 0 0

PROC/PROC proc Defaults 0 0

Label=swap-sda2 Swap Defaults 0 0

~

~

[Root@instuctor ~]# Mount-o Remount/dev/shm

[Root@instuctor ~]# Df-h

FileSystem Size Used Avail use% mounted on

/DEV/SDA1 17G 15G 1.2G 93%/

Tmpfs 2.2G 209M 2.0G 10%/DEV/SHM

After expanding the/DEV/SHM, try to start the database again, no problem.

[Oracle@instuctor ~]$ Sqlplus/as SYSDBA

Sql*plus:release 11.2.0.3.0 Production on Mon Nov 19 10:02:33 2012

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

Connected to a idle instance.

Sql> Startup

ORACLE instance started.

Total System Global area 939495424 bytes

Fixed Size 2233960 bytes

Variable Size 616565144 bytes

Database buffers 314572800 bytes

Redo buffers 6123520 bytes

Database mounted.

Database opened.