ORA-01092 - ORACLE Instance Terminated - Disconnection Forced

We had a good working Oracle 8i (8.1.7) database on Windows 2000 (SP 2) Inter Xeon server. A large delete operation was

initiated (deletion of 931,000 records; around 400 MB) which failed in the middle with some error messages, i don't remember.

I should have specified a special rollback segment created for this transection, but i forgot to do it. After that oracle

gives the following error in SQL Plus after I try to log in (same msg even after several reboots)

ORA-01092: ORACLE instance terminated. Disconnection forced

Here is the log file,

Dump file C:oracleadminillingdumpillingALRT.LOG
Fri Oct 13 14:19:40 2006
ORACLE V8.1.7.0.0 - Production vsnsta=0
vsnsql=e vsnxtr=3

[Code]....

Notice that that the database mounts successfully on "startup mount dbname" but it terminates with the above error messages

immediately when I give the "alter database open" command from server manager. Directly giving the "startup open dbname"

command also gives the same error message and log file.

Some one recommended adding the following line to Init.ora file for the db (if some corruption in rollback tablespace has occured)

fast_start_parallel_rollback= false

You may have seen this line in the log file above. However, it has no effect on the database functioning.