Oracle not available Shared memory realm doesnot exist

After Restarting the machine, when I tried to log on database through sql I got the
problem.It says

“oracle not available”
“Shared memory realm does not exist”

Solution done by me after searching google:–

1.> through Sql
conn / as sysdba;

2.> startup nomount;
It shows the message

ORACLE instance started.

Total System Global Area 113246208 bytes

Fixed Size 787708 bytes

Variable Size 61864708 bytes

Database Buffers 50331648 bytes

Redo Buffers 262144 bytes

3.>alter database mount;

4.> alter database open;

Now your data base is ready to use.

28 thoughts on “Oracle not available Shared memory realm doesnot exist

  1. After doing “alter database open;”, the following message appears:

    ERROR at line 1:

    And after, when I try to connect to my database (“conn mydatabase;”), the same errors (“ORACLE not available” and “shared memory realm does not exist”) return.

  2. 2.> startup nomount;
    after this step I am getting the error stating :
    XE Edition memory parameter invalid or not specified

  3. what does that 1.>through sql mean. Sorry but i am a noob in this. please explain as once I enter the username and password in sql*plus i get the same error. so where should I put this command?? help

  4. after “alter database open” it is saying an error “redo log redo error block 3 count 8192” what does it mean? how to find solution for this problm? please tell me

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