oracle error - ORA-00286: no members available, or no member contains valid data

ORA-00286:	no members available, or no member contains valid data
Cause:	None of the members of a redo log file group are available, or the available members do not contain complete data.
Action:	If a member is temporarily offline, attempt to make it available. Make sure that the correct filenames are being used, especially if the redo log file is being accessed from a remote location.

oracle error - ORA-00285: TIME not given as a string constant

ORA-00285:	TIME not given as a string constant
Cause:	UNTIL TIME was not followed by a string constant for the time.
Action:	Enter the time enclosed in single quotation marks.

ORA-00284:	recovery session still in progress
Cause:	An error during recovery was determined to be minor enough to allow the current recovery session to continue.
Action:	More specific messages will accompany this message. Refer to the other messages for the appropriate action.