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.
Satendrakumar's Weblog 
After doing “alter database open;”, the following message appears:
“…
ERROR at line 1:
ORA-03113
…”
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.
awesome post …….. thumbs UP !
Thanks.. Glad it Helped to someone …
Thanks dude done great job
good post worked alot for me
thanks dude.
Thank You Soooo Much… Both thumbs up for . it 100% working
Thank you ..!!!! satendra .. it was great help
it was great help
2.> startup nomount;
after this step I am getting the error stating :
XE Edition memory parameter invalid or not specified
check this …
http://shanghosh.blogspot.ae/2009/08/ora-44412-xe-edition-memory-parameter.html
awesome .perfect .thanks mate
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
Go to command prompt of windows (type “cmd” in start-up box) and type “sqlplus”.
I has to do “sqlplus / as sydba” in terminal.
* sqlplus / as sysdba
no need to do any thing go to services,msc, stop and start Oracle Service
Really big thanks for you.
Thanks but after reboot, still the same problem for me.
For permanent solution, you can add $ORACLE_SID:$ORACLE_HOME:Y to /etc/oratab and then start (dbstart $ORACLE_HOME) or stop (dbshut $ORACLE_HOME) when you want. source: http://www.makina-corpus.org/blog/howto-install-oracle-11g-ubuntu-linux-1204-precise-pangolin-64bits
Thank you very much dear
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
sorry its “redo log read error block 2 count 8192” I am mistaken
It’s does not happen after conn / as sysdba it showed 6 events errors and then on the startup nomount it showed 5 error with error in modifying file.
great work
But I want permanent solution instead of performing these steps every time we start computer
and this is the simplest,easiest and permanent solution to this problem..
thank u it works successfully
thank u so much.after searching of so much content .finaly ur answer helped me.now its working