环境说明：
OS:aix 6.1
DB:Oracle 10gR2 裸设备
使用rman备份整个数据库备份失败，提示71数据文件失败，单独备份这个数据文件
$ rman target /
Recovery Manager: Release 10.2.0.1.0 - Production on Thu Nov 7 09:14:31 2013
Copyright (c) 1982, 2005, Oracle. All rights reserved.
connected to target database: ORCL (DBID=1237792397, not open)
RMAN> backup as copy datafile 71 format '/backup_dir/in71_%U';
Starting backup at 07-NOV-13
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: sid=1086 devtype=DISK
channel ORA_DISK_1: starting datafile copy
input datafile fno=00071 name=/dev/rdata_03
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03009: failure of backup command on ORA_DISK_1 channel at 11/07/2013 09:18:10
ORA-19501: read error on file "/dev/rdata_03", blockno 178305 (blocksize=8192)
ORA-27063: number of bytes read/written is incorrect
IBM AIX RISC System/6000 Error: 5: I/O error
Additional information: -1
Additional information: 1048576
RMAN> backup check logical validate datafile 71;
Starting backup at 07-NOV-13
using channel ORA_DISK_1
channel ORA_DISK_1: starting full datafile backupset
channel ORA_DISK_1: specifying datafile(s) in backupset
input datafile fno=00071 name=/dev/rdata_03
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03009: failure of backup command on ORA_DISK_1 channel at 11/07/2013 09:47:03
ORA-19501: read error on file "/dev/rdata_03", blockno 178305 (blocksize=8192)
ORA-27063: number of bytes read/written is incorrect
IBM AIX RISC System/6000 Error: 5: I/O error
Additional information: -1
Additional information: 1048576
查询坏块个数
SQL> select * from v$database_block_corruption;
no rows selected
没有查询到逻辑坏块，猜测为物理坏块，数据库层面还认为是好的数据库造成了读的时候提示I/O error
检查71号文件的数据块个数
SQL> select bytes/8192 from v$datafile where file#=71;
BYTES/8192
----------
1280000
验证裸设备是否可以读
$ dbv file=/dev/rdata_03 blocksize=8192
DBVERIFY: Release 10.2.0.1.0 - Production on Thu Nov 7 09:48:08 2013
Copyright (c) 1982, 2005, Oracle. All rights reserved.
DBVERIFY - Verification starting : FILE = /dev/rdata_03
DBV-00102: File I/O error on FILE (/dev/rdata_03) during verification read operation (-2)
找出坏块，使用Oracle自带的工具
$ dbv file=/dev/rdata_03 blocksize=8192
DBVERIFY: Release 10.2.0.1.0 - Production on Thu Nov 7 09:48:08 2013
Copyright (c) 1982, 2005, Oracle. All rights reserved.
DBVERIFY - Verification starting : FILE = /dev/rdata_03
DBV-00102: File I/O error on FILE (/dev/rdata_03) during verification read operation (-2)
同时在另一个窗口中查看
$ ps -ef | grep dbv
oracle 598170 593980 38 09:57:42 pts/1 0:00 dbv file=/dev/rdata_03 blocksize=8192
oracle 1712282 581750 0 09:57:46 pts/0 0:00 grep dbv
$ truss -faieo /tmp/strace.out -p 598170
598170: klseek(5, 746045440, 0, 0x0FFFFFFFFFFF9530) = 0
...skipping...
598170: kread(5, " ( 011 ???D 5 ??.., 8192) = 8192
598170: klseek(5, 1461190656, 0, 0x0FFFFFFFFFFF9530) = 0
598170: kread(5, " ( 011 ???D 5 ??.., 8192) Err#5 EIO
598170: kwrite(2, "n D B V - 0 0 1 0 2 : ", 12) = 12
598170: kwrite(2, " F i l e I / O e r r".., 24) = 24
598170: kwrite(2, " / d e v / r d a t a _ c".., 15) = 15
598170: kwrite(2, " ) d u r i n g ", 9) = 9
598170: kwrite(2, " v e r i f i c a t i o n".., 17) = 17
598170: kwrite(2, " o p e r a t i o n (", 12) = 12
598170: kwrite(2, " -", 1) = 1
598170: kwrite(2, " 2", 1) = 1
598170: kwrite(2, " )", 1) = 1
598170: kwrite(2, "n", 1) = 1
598170: close(5) = 0
598170: close(4) = 0
598170: kfcntl(1, F_GETFL, 0x00000000101A2087) = 67110914
598170: kfcntl(2, F_GETFL, 0x00000000101A2087) = 67110914
598170: _exit(1)
...skipping...
598170: kread(5, " ( 011 ???D 5 ??.., 8192) = 8192
598170: klseek(5, 1461190656, 0, 0x0FFFFFFFFFFF9530) = 0
598170: kread(5, " ( 011 ???D 5 ??.., 8192) Err#5 EIO
598170: kwrite(2, "n D B V - 0 0 1 0 2 : ", 12) = 12
598170: kwrite(2, " F i l e I / O e r r".., 24) = 24
598170: kwrite(2, " / d e v / r d a t a _ c".., 15) = 15
598170: kwrite(2, " ) d u r i n g ", 9) = 9
598170: kwrite(2, " v e r i f i c a t i o n".., 17) = 17
598170: kwrite(2, " o p e r a t i o n (", 12) = 12
598170: kwrite(2, " -", 1) = 1
598170: kwrite(2, " 2", 1) = 1
598170: kwrite(2, " )", 1) = 1
598170: kwrite(2, "n", 1) = 1
598170: close(5) = 0
598170: close(4) = 0
598170: kfcntl(1, F_GETFL, 0x00000000101A2087) = 67110914
598170: kfcntl(2, F_GETFL, 0x00000000101A2087) = 67110914
598170: _exit(1)
找到开始的坏块
1461190656/8192=178368
说明第一个坏块为178368，验证最后的坏块，最大的数据块是1280000
$ dbv file=/dev/rdata_03 blocksize=8192 start=1461190656
DBVERIFY: Release 10.2.0.1.0 - Production on Thu Nov 7 10:10:58 2013
Copyright (c) 1982, 2005, Oracle. All rights reserved.
DBV-00102: File I/O error on FILE (/dev/rdata_03) during start read operation (-2)
$ dbv file=/dev/rdata_03 blocksize=8192 start=194719
DBVERIFY: Release 10.2.0.1.0 - Production on Thu Nov 7 10:52:56 2013
Copyright (c) 1982, 2005, Oracle. All rights reserved.
DBVERIFY - Verification starting : FILE = /dev/rdata_03
DBVERIFY - Verification complete
Total Pages Examined : 1085282
Total Pages Processed (Data) : 1272
Total Pages Failing (Data) : 0
Total Pages Processed (Index): 127
Total Pages Failing (Index): 0
Total Pages Processed (Other): 1082867
Total Pages Processed (Seg) : 0
Total Pages Failing (Seg) : 0
Total Pages Empty : 1016
Total Pages Marked Corrupt : 0
Total Pages Influx : 0
Highest block SCN : 1845997064 (2919.1845997064)
采用数据拼接的模式重构这个数据文件
$ dd if=/dev/zero of=/backup_dir/rdata_03_02 bs=8192 count=16343
16343+0 records in.
16343+0 records out.
$ dd if=/dev/rdata_03 of=/backup_dir/rdata_03_03 bs=8192 skip=194710
1116010+0 records in.
1116010+0 records out.
$ dd if=/dev/rdata_03 of=/backup_dir/rdata_03_01 bs=8192 count=178367
178367+0 records in.
178367+0 records out.
$ cat /backup_dir/rdata_03_01 /backup_dir/rdata_03_02 /backup_dir/rdata_03_03 > /backup_dir/rdata_03_ct
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