接到朋友恢复请求，aix 5.3,Oracle 10.2.0.1平台，数据库启动报ORA-01115 ORA-01110 ORA-27067错误，数据库无法正常打开，通过分析，是由于10201在aix上面的bug导致，通过技巧规避，完美解决给问题，数据0丢失
数据库报错alert日志

Mon Aug 10 13:25:22 2015
ALTER DATABASE   MOUNT
Mon Aug 10 13:25:29 2015
Setting recovery target incarnation to 1
Mon Aug 10 13:25:29 2015
Successful mount of redo thread 1, with mount id 432339141
Mon Aug 10 13:25:29 2015
Database mounted in Exclusive Mode
Completed: ALTER DATABASE   MOUNT
Mon Aug 10 13:25:36 2015
alter database open
Mon Aug 10 13:25:36 2015
Beginning crash recovery of 1 threads
 parallel recovery started with 15 processes
Mon Aug 10 13:25:37 2015
Started redo scan
Mon Aug 10 13:25:52 2015
Completed redo scan
 7889582 redo blocks read, 75305 data blocks need recovery
Mon Aug 10 13:25:53 2015
Errors in file /dc/admin/datacent/bdump/datacent_p002_144124.trc:
ORA-01115: IO error reading block from file 2 (block # 40704)
ORA-01110: data file 2: '/dc/oradata/datacent/undotbs01.dbf'
ORA-27067: size of I/O buffer is invalid
Additional information: 2
Additional information: 1572864
Mon Aug 10 13:25:53 2015
Aborting crash recovery due to slave death, attempting serial crash recovery
Mon Aug 10 13:25:53 2015
Beginning crash recovery of 1 threads
Mon Aug 10 13:25:53 2015
Started redo scan
Mon Aug 10 13:26:09 2015
Completed redo scan
 7889582 redo blocks read, 75305 data blocks need recovery
Mon Aug 10 13:26:12 2015
Aborting crash recovery due to error 1115
Mon Aug 10 13:26:12 2015
Errors in file /dc/admin/datacent/udump/datacent_ora_123384.trc:
ORA-01115: IO error reading block from file 2 (block # 39077)
ORA-01110: data file 2: '/dc/oradata/datacent/undotbs01.dbf'
ORA-27067: size of I/O buffer is invalid
Additional information: 2
Additional information: 1310720
ORA-1115 signalled during: alter database open...

这里报的前面两个错误ORA-01115 ORA-01110我们都非常熟悉，类似数据库启动遇到坏块或者io错误之时可能就会报如此错误。但是ORA-27067确实不多见，从mos上看，很多是由于rman备份之时的bug可能导致该错误。

dbv检测undo坏块文件

DBVERIFY: Release 10.2.0.1.0 - Production on Mon Aug 10 23:18:15 2015
Copyright (c) 1982, 2003, Oracle and/or its affiliates.  All rights reserved.
DBVERIFY - Verification starting : FILE = /dc/oradata/datacent/undotbs01.dbf
DBVERIFY - Verification complete
Total Pages Examined         : 329600
Total Pages Processed (Data) : 0
Total Pages Failing   (Data) : 0
Total Pages Processed (Index): 0
Total Pages Failing   (Index): 0
Total Pages Processed (Other): 327504
Total Pages Processed (Seg)  : 17
Total Pages Failing   (Seg)  : 0
Total Pages Empty            : 2096
Total Pages Marked Corrupt   : 0
Total Pages Influx           : 0
Total Pages Encrypted        : 0
Highest block SCN            : 1887888 (0.1887888)

这里可以看到，undo文件本身并没有逻辑和物理的坏块,证明因为数据库异常的原因，可能是由于ORA-27067: size of I/O buffer is invalid导致。根据官方文档ORA-01115 ORA-27067 DURING PARALLEL INSTANCE RECOVERY AFTER INSTANCE CRASH中的解释，我们基本上可以确定很可能是由于10.2.0.1在aix平台的jfs2系统中，由于大量事务操作，突然abort掉数据库（也可能断电），从而数据库在启动的时候进行实例恢复，而由于内部的bug，导致实例恢复无法成功。通过我们处理后的，数据库完美启动，数据0丢失

数据库启动日志

Mon Aug 10 16:34:14 2015
alter database open
Mon Aug 10 16:34:14 2015
Beginning crash recovery of 1 threads
 parallel recovery started with 15 processes
Mon Aug 10 16:34:14 2015
Started redo scan
Mon Aug 10 16:34:27 2015
Completed redo scan
 7889582 redo blocks read, 0 data blocks need recovery
Mon Aug 10 16:34:27 2015
Started redo application at
 Thread 1: logseq 664704, block 1286922
Mon Aug 10 16:34:27 2015
Recovery of Online Redo Log: Thread 1 Group 4 Seq 664704 Reading mem 0
  Mem# 0 errs 0: /dev/rredo04
Mon Aug 10 16:34:32 2015
Recovery of Online Redo Log: Thread 1 Group 5 Seq 664705 Reading mem 0
  Mem# 0 errs 0: /dev/rredo05
Mon Aug 10 16:34:38 2015
Recovery of Online Redo Log: Thread 1 Group 6 Seq 664706 Reading mem 0
  Mem# 0 errs 0: /dev/rredo06
Mon Aug 10 16:34:40 2015
Completed redo application
Mon Aug 10 16:34:40 2015
Completed crash recovery at
 Thread 1: logseq 664706, block 1017805, scn 8554793334
 0 data blocks read, 0 data blocks written, 7889582 redo blocks read
Mon Aug 10 16:34:40 2015
Thread 1 advanced to log sequence 664707
Thread 1 opened at log sequence 664707
  Current log# 1 seq# 664707 mem# 0: /dev/rredo01
Successful open of redo thread 1
Mon Aug 10 16:34:40 2015
MTTR advisory is disabled because FAST_START_MTTR_TARGET is not set
Mon Aug 10 16:34:40 2015
SMON: enabling cache recovery
Mon Aug 10 16:34:40 2015
Successfully onlined Undo Tablespace 1.
Mon Aug 10 16:34:40 2015
SMON: enabling tx recovery
Mon Aug 10 16:34:41 2015
Database Characterset is ZHS32GB18030
replication_dependency_tracking turned off (no async multimaster replication found)
WARNING: AQ_TM_PROCESSES is set to 0. System operation might be adversely affected.
Mon Aug 10 16:34:41 2015
SMON: Parallel transaction recovery tried
Mon Aug 10 16:34:42 2015
db_recovery_file_dest_size of 2048 MB is 0.00% used. This is a
user-specified limit on the amount of space that will be used by this
database for recovery-related files, and does not reflect the amount of
space available in the underlying filesystem or ASM diskgroup.
Mon Aug 10 16:34:42 2015
Completed: alter database open