Recovery: SYSTEM Tablespace Missing 
One or more files of the SYSTEM tablespace has been damaged or lost due to a media error.
Backups of the affected files exist. All offline redo log files that have been written since the last backup are available uninterrupted. The control files and all online redo log files are undamaged.
Recovery Procedure
Because the SYSTEM tablespace is affected, the recovery must take place with the database closed. If a backup of the missing files and all redo log entries are available, a complete recovery is possible.
shutdown abort
ABORT is required because the loss of individual files from the tablespace means that the changes from SGA can no longer be recorded, and the database cannot be closed properly as a result.
– Last backup of the SYSTEM tablespace
– Offline redo log files of all instances archived since the last backup
Use the SAP utility BRRESTORE (see
Command Options for BRRESTORE).connect internal
startup mount
recover database;
alter database open;

Please note: in most cases, SAPDBA can be used to correct media errors affecting the data files of a user tablespace. Therefore, we recommend using the SAPDBA recovery functions (see
SAPDBA Database Recovery).