Ora-01034 and ora-27101 error messages when I try to connect to the database. It always displays such messages as “ora-01034 – Oracle not available” and “ora-27101 – shared memory real does not exist”
unable to connect to my Oracle database
because there are a lot of problems with firewalls, I’ll take a look this time and find that there is no interception at all. After checking the monitoring, the database instance is also running<It’s a strange thing. It’s still good just now. It won’t work after restarting the machine. After searching the Internet, the problem is solved

the solution is not troublesome…
let’s take a look at Oracle first_ BASE\ORACLE_ If there is this error in the oradim.log file under home/database,
ora-12640: failed to verify adapter initialization,
then the problem is it.
go to Oracle_ BASE\ORACLE_ Find the sqlnet.ora file under home/network/Admin
and put the sqlnet.authentication_ Services = (NTS) is changed to
sqlnet.authentication_ Services = (none)
and then manually restart which database service you have; Control panel – > Management tools – > In the service, then change the startup account of this service to your account… In fact, if you don’t change it, there’s probably no problem. I didn’t change it

after looking at this method, there are probably two reasons for the error: the account has been modified, and the instance has changed

Note: the above contents are quoted

Postscript:

Just today, my 8i database also had errors: “ora-01034 – Oracle not available” and “ora-27101 – shared memory real does not exist”. Then I found the above content on the Internet and solved the problem according to what I said. Very happy

One more thing to add is that my oradim.log file is in the directory orant/database, while the file sqlnet.ora is in the directory orant/network/Admin

Next. The possible cause of this problem in my database is: shut down the database abnormally (shut down directly without shutting down the database)

On this issue, itpub has the following statement: (but I haven’t tested it)

1. Instance not started

sqlplus/nolog
connect/as sysdba
startup

2. Recently, the antivirus software killed Oracle down, and Oracle did not report an error

Just start up

3. Execute the following statement to start the database
sqlplus/nolog
connect/as SYSDBA
startup force

Because sqlplus cannot be executed in CMD, the window execution mode sqlplusw is adopted

Basically use LS

sqlplusw/nolog
connect/as sysdba
startup force

In addition, we also found a record about this problem of an expert (although I didn’t test it, I believe what he said is feasible, and the “abnormal shutdown” mentioned in him is similar to the reason I said above, “abnormal shutdown of the database (direct shutdown without closing the database)”):

Last night, I was busy writing programs until more than 12 o’clock. A friend said there was something wrong with his database, so he used JoinNet to check it. The discovery is ora-27101. First, sort out the operation steps for your reference

1。 First, check the alert.log in Oracle/admin/SID/bdump and find that there is no information about the last database startup. That is to say, the computer may have been shut down abnormally

2。 Enter the CMD mode, sqlplus/nolog, connect/as SYSDBA, execute startup, or 27101 error. It is preliminarily determined that the init.ora file is abnormal, and the init.ora file before copy is overlapped

3。 Enter the CMD mode, sqlplus/nolog, connect/as SYSDBA, and execute startup pfile = C:: (Oracle, admin, Sid, pfile, init. ORA). The startup is successful