ORA-38701: Flashback database log 518 seq 6752 thread 1:

ORA-38701: Flashback database log 518 seq 6752 thread 1: "/pac/lci1d1/arch/LCI1D1/flashback/o1_mf_9zc63rhb_.flb"

ORA-27037: unable to obtain file status

Cause of The Problem
The above errors occurred due to a well identified bug. If there is any I/O error that is preventing write to the flashback logs, the instance will crash. Losing the current flashback log will cause the instance to crash. Also during database startup if flashback logs are inaccessible then instance will crush.

Solution of The Problem

Solution A)-Upgarde Database Version:
This bug is affected from database version 10.1.0.1 to 10.1.0.4
It is fixed in database version 10gR2. So upgrade your database version.

Solution B)-Disable Flashback and restart the instance.
1)If you don't have the situation to upgrade the database then start the database in mount stage.
SQL> startup mount;

2)Turn off the Flashback
SQL> alter database flashback off;

3)Turn on the Flashback
SQL> alter database flashback on;

4)Startup the database
SQL>alter database open;

Or, SQL>shutdown
SQL>startup

Note:
After disabling flashback if you have guaranteed restore point then you still might get the error ORA-38760: This database instance failed to turn on flashback database while starting up the database. In this case you have to drop the guaranteed restore point.

You can see the available guaranteed restore point by,
select NAME,SCN,GUARANTEE_FLASHBACK_DATABASE,DATABASE_INCARNATION# from v$restore_point;
Then drop the guaranteed restore point by,
DROP RESTORE POINT NAME_OF_THE_GUARANTEED_RESTORE_POINT;
Now start your database.