报错如下：
Sat May 15 01:07:11 2010
Errors in file /oracle/admin/scdcdata/udump/scdcdata_ora_581844.trc:
ORA-19883: Message 19883 not found;  product=RDBMS; facility=ORA
; arguments: [/oradata/scdcdata/scdc_ods01.dbf]
ORA-01115: IO error reading block from file /oradata/scdcdata/scdc_ods01.dbf (block # 3256313)
ORA-27091: unable to queue I/O
ORA-27069: attempt to do I/O beyond the range of the file
Additional information: 3256313
Additional information: 1
Additional information: 3243521
Sat May 15 01:17:33 2010
Starting control autobackup
Control autobackup written to DISK device
        handle '/usr/oracle/scdcdata/flashback_area/SCDCDATA/autobackup/2010_05_15/o1_mf_s_719025453_5yv1fh6o_.bkp'

查找metalink:

Bug 8354642  ORA-19883 ORA-1115/ORA-27091/ORA-27069 in alert log while running RMAN backup

 This note gives a brief overview of bug 8354642. 
 The content was last updated on: 10-JUL-2009
 Click here for details of each of the sections below.

Affects:

Product (Component)	Oracle Server (Rdbms)
Range of versions believed to be affected	Versions >= 10.2 but < 11.2
Versions confirmed as being affected	10.2.0.4
Platforms affected	Generic (all / most platforms affected)

Fixed:

This issue is fixed in

11.2 (Future Release)

Description

Errors ORA-19883 ORA-1115 ORA-27091 and ORA-27069 can be reported in the alert log 
while running RMAN backup if a datafile in a locally managed tablespace (LMT)
is extended during backup like a datafile resize or autoextend.  

Example from alert log:

Errors in file :
    ORA-19883: Unused Block Optimization stopped for datafile 
    ORA-01115: IO error reading block from file  (block # )
    ORA-27091: unable to queue I/O
    ORA-27069: attempt to do I/O beyond the range of the file
    Additional information: 
    Additional information: 1
    Additional information: 

Trace file may show:

"Error: Bitmap  for file  at block  of datafile  
has incorrect block type, expected: 30, got:"

RMAN unused block optimization is then stopped due to the I/O errors when reading tail 
bitmaps. However the backup is VALID and RMAN backup succeeds with no errors.

References

Bug:8354642 (This link will only work for PUBLISHED bugs)
Note:245840.1 Information on the sections in this article