Parnassusdata Software Database Recovery Team
STARTUP HANGS
If the database hangs on startup:
1.) Instruct the customer to do a STARTUP NOMOUNT (to see if the
background processes will start).
2.) Try an ALTER DATABASE MOUNT.
3.) Try doing some SELECTs from any v$ view.
4.) If this works, you can do an alter session
set _trace_enabled=true in the init.ora.
5.) Then do an ALTER DATABASE OPEN.
6.) After the db has been hanging for a minute or so, use CTRL/C (depress
and hold the CTRL key while pressing the 'c' key) to stop the
process. See if the trace tells you which SQL statement it is
hanging on (it could be dictionary corrupt).
TABLESPACE, LOST DATAFILE
After a tablespace has been created with its datafiles, the datafiles
must exist for the life of the tablespace unless all objects in the
tablespace are dropped first. The supported way to recover from a
lost datafile is to have the customer restore the old datafile from
an older, cold backup (full backup) or a hot backup (single tablespace
backup while the database is online).
If the database is in NOARCHIVELOG mode, you will only succeed in
recovering the db if the datafile in the redo to be applied to it is
within the range of your online REDO logs.
If the customer has no backups of the datafile that is corrupt, there
is a chance the events 10231 and 10233 can be set to skip the corrupted
blocks so an export can be done. If that doesn't work or the corruption
is in the datafile header, they will loose their data.
CONTROL FILES
If you are mirroring control files, and one is bad, delete it and copy
the good one in its place.
If you need to create a new control file or change the MAXLOGFILES,
MAXLOGMEMBERS, MAXDATAFILES, MAXINSTANCES, or MAXLOGHISTORY parameters: