月归档：四月 2013

模拟enq: TX – allocate ITL entry等待

发表于 2013 年 4 月 10 日 由 惜分飞

今天在分析一份awr中发现了较为明显的enq: TX – allocate ITL entry等待,这里通过试验详细重现了enq: TX – allocate ITL entry等待
创建测试对象

SQL> create table t_xifenfei (name char(2000)) pctfree 0 initrans 1;

Table created.

SQL> insert into t_xifenfei select object_name from all_objects    where rownum < 5;

4 rows created.

SQL> commit;

Commit complete.

SQL> alter system flush buffer_cache;

System altered.

SQL>  select distinct dbms_rowid.rowid_relative_fno(rowid) file#,
  2  dbms_rowid.rowid_block_number(rowid) block# from t_xifenfei;

     FILE#     BLOCK#
---------- ----------
         4         32

bbed查看block

BBED> set block 32
        BLOCK#          32

BBED> map
 File: /u01/oracle/oradata/XFF/users01.dbf (0)
 Block: 32                                    Dba:0x00000000
------------------------------------------------------------
 KTB Data Block (Table/Cluster)

 struct kcbh, 20 bytes                      @0       

 struct ktbbh, 72 bytes                     @20      

 struct kdbh, 14 bytes                      @100     

 struct kdbt[1], 4 bytes                    @114     

 sb2 kdbr[4]                                @118     

 ub1 freespace[38]                          @126    --该block空闲空间为38byte 

 ub1 rowdata[8024]                          @164     

 ub4 tailchk                                @8188    


BBED> p ktbbh
struct ktbbh, 72 bytes                      @20      
   ub1 ktbbhtyp                             @20       0x01 (KDDBTDATA)
   union ktbbhsid, 4 bytes                  @24      
      ub4 ktbbhsg1                          @24       0x0000d318
      ub4 ktbbhod1                          @24       0x0000d318
   struct ktbbhcsc, 8 bytes                 @28      
      ub4 kscnbas                           @28       0xc0320e3b
      ub2 kscnwrp                           @32       0x0b2c
   b2 ktbbhict                              @36       2
   ub1 ktbbhflg                             @38       0x32 (NONE)
   ub1 ktbbhfsl                             @39       0x00
   ub4 ktbbhfnx                             @40       0x01000019
   struct ktbbhitl[0], 24 bytes             @44       --1个itl slot为24byte
      struct ktbitxid, 8 bytes              @44      
         ub2 kxidusn                        @44       0x0015
         ub2 kxidslt                        @46       0x0019
         ub4 kxidsqn                        @48       0x00000005
      struct ktbituba, 8 bytes              @52      
         ub4 kubadba                        @52       0x0080009d
         ub2 kubaseq                        @56       0x0002
         ub1 kubarec                        @58       0x28
      ub2 ktbitflg                          @60       0x2004 (KTBFUPB)
      union _ktbitun, 2 bytes               @62      
         b2 _ktbitfsc                       @62       0
         ub2 _ktbitwrp                      @62       0x0000
      ub4 ktbitbas                          @64       0xc0320e4e
   struct ktbbhitl[1], 24 bytes             @68       --有两个itl slot
      struct ktbitxid, 8 bytes              @68      
         ub2 kxidusn                        @68       0x0000
         ub2 kxidslt                        @70       0x0000
         ub4 kxidsqn                        @72       0x00000000
      struct ktbituba, 8 bytes              @76      
         ub4 kubadba                        @76       0x00000000
         ub2 kubaseq                        @80       0x0000
         ub1 kubarec                        @82       0x00
      ub2 ktbitflg                          @84       0x0000 (NONE)
      union _ktbitun, 2 bytes               @86      
         b2 _ktbitfsc                       @86       0
         ub2 _ktbitwrp                      @86       0x0000
      ub4 ktbitbas                          @88       0x00000000

通过bbed我们可以得出如下结论：
1.该block剩余38 byte 空闲空间可以用来存放数据
2.该block 初始化 itl 为2(和我们设置的1不相符)
3.一个itl slot为24byte

更新表记录

--session 1
SQL> select trim(name) from t_xifenfei;

TRIM(NAME)
--------------------------------------------------------------------------------
ICOL$
I_USER1
CON$
UNDO$

SQL> update t_xifenfei set name='WWW.XIFENFEI.COM' WHERE name='ICOL$';

1 row updated.

--session 2
SQL> update t_xifenfei set name='www.orasos.com' where name='UNDO$';

1 row updated.

--session 3
SQL> update t_xifenfei set name='www.xifenfei.com' where name='CON$';

1 row updated.

--session 4
SQL> update t_xifenfei set name='www.xifenfei.com' where name='I_USER1';
--hang住

--session 5
SQL> select event from v$session where  event like 'enq%';

EVENT
----------------------------------------------------------------
enq: TX - allocate ITL entry

通过这里可以看到我们模拟了4个update 该block操作(均未提交)，前面三个可以正常的update操作，第四个出现了enq: TX – allocate ITL entry等待,根据我们知识分析(未提交事务的itl不能覆盖,一个dml操作需要一个itl),这里使用了3个itl slot,而我们已经知道一个itl 需要24byte，该block初始化有2个itl,现在这里有3个dml操作成功,即占用了3个itl,所以该block的剩余空间只有38-24=14 byte<24byte,因此无法分配第四个itl slot从而出现了enq: TX - allocate ITL entry等待
bbed验证上述分析

BBED> map
 File: /u01/oracle/oradata/XFF/users01.dbf (0)
 Block: 32                                    Dba:0x00000000
------------------------------------------------------------
 KTB Data Block (Table/Cluster)

 struct kcbh, 20 bytes                      @0       

 struct ktbbh, 96 bytes                     @20      

 struct kdbh, 14 bytes                      @124     

 struct kdbt[1], 4 bytes                    @138     

 sb2 kdbr[4]                                @142     

 ub1 freespace[14]                          @150     

 ub1 rowdata[8024]                          @164     

 ub4 tailchk                                @8188    


BBED> p ktbbh
struct ktbbh, 96 bytes                      @20      
   ub1 ktbbhtyp                             @20       0x01 (KDDBTDATA)
   union ktbbhsid, 4 bytes                  @24      
      ub4 ktbbhsg1                          @24       0x0000d318
      ub4 ktbbhod1                          @24       0x0000d318
   struct ktbbhcsc, 8 bytes                 @28      
      ub4 kscnbas                           @28       0xc0320eb0
      ub2 kscnwrp                           @32       0x0b2c
   b2 ktbbhict                              @36       3
   ub1 ktbbhflg                             @38       0x32 (NONE)
   ub1 ktbbhfsl                             @39       0x00
   ub4 ktbbhfnx                             @40       0x01000019
   struct ktbbhitl[0], 24 bytes             @44      
      struct ktbitxid, 8 bytes              @44      
         ub2 kxidusn                        @44       0x0003
         ub2 kxidslt                        @46       0x001f
         ub4 kxidsqn                        @48       0x00000208
      struct ktbituba, 8 bytes              @52      
         ub4 kubadba                        @52       0x00800027
         ub2 kubaseq                        @56       0x0414
         ub1 kubarec                        @58       0x01
      ub2 ktbitflg                          @60       0x0001 (NONE)
      union _ktbitun, 2 bytes               @62      
         b2 _ktbitfsc                       @62       0
         ub2 _ktbitwrp                      @62       0x0000
      ub4 ktbitbas                          @64       0x00000000
   struct ktbbhitl[1], 24 bytes             @68      
      struct ktbitxid, 8 bytes              @68      
         ub2 kxidusn                        @68       0x000a
         ub2 kxidslt                        @70       0x000f
         ub4 kxidsqn                        @72       0x00000185
      struct ktbituba, 8 bytes              @76      
         ub4 kubadba                        @76       0x0080008a
         ub2 kubaseq                        @80       0x01a6
         ub1 kubarec                        @82       0x0c
      ub2 ktbitflg                          @84       0x0001 (NONE)
      union _ktbitun, 2 bytes               @86      
         b2 _ktbitfsc                       @86       0
         ub2 _ktbitwrp                      @86       0x0000
      ub4 ktbitbas                          @88       0x00000000
   struct ktbbhitl[2], 24 bytes             @92      
      struct ktbitxid, 8 bytes              @92      
         ub2 kxidusn                        @92       0x0008
         ub2 kxidslt                        @94       0x002a
         ub4 kxidsqn                        @96       0x00000217
      struct ktbituba, 8 bytes              @100     
         ub4 kubadba                        @100      0x008000cc
         ub2 kubaseq                        @104      0x0291
         ub1 kubarec                        @106      0x12
      ub2 ktbitflg                          @108      0x0001 (NONE)
      union _ktbitun, 2 bytes               @110     
         b2 _ktbitfsc                       @110      0
         ub2 _ktbitwrp                      @110      0x0000
      ub4 ktbitbas                          @112      0x00000000

可以看到剩余空间为14byte，事务槽为3个，因此上述分析为正确。

提交会话测试

--session 1
SQL> commit;

Commit complete.

--session 4
SQL> update t_xifenfei set name='www.xifenfei.com' where name='I_USER1';


1 row updated.

证明commit掉事务后,itl slot可以重利用

总结说明
enq: TX – allocate ITL entry为分配ITL条目的等待，因为PCTFREE不足，BLOCK中没有足够空间分配ITL，ORACLE只能重用ITL，但是这个时候由于没有COMMIT，无法重用ITL，所以会出现allocate ITL等待事件。要解决此类问题，我们可以考虑增加PCTFREE和initrans大小,需要注意该修改只能对于新block生效,已经存放数据的block不会发生改变.另外可以考虑修改业务逻辑,减少频繁访问

发表在 Oracle性能优化 | 标签为 | 2 条评论

使用PXE刷XD

发表于 2013 年 4 月 5 日 由 惜分飞

需要安装服务

bind
dhcp
system-config-netboot
tftp-server

dhcp配置

[root@xifenfei ~]# more /etc/redhat-release 
Red Hat Enterprise Linux AS release 4 (Nahant Update 8)

[root@xifenfei ~]# more /etc/dhcpd.conf
subnet 192.168.30.0 netmask 255.255.255.0 {
  range dynamic-bootp 192.168.30.101 192.168.30.126;
  option broadcast-address 192.168.30.255;
  option routers 192.168.30.1;
  next-server 192.168.30.90;
  filename = "pxelinux.0";
}
--以下直接复制无需修改
ddns-update-style none;
subnet 10.182.77.0 netmask 255.255.255.0 {}
subnet 10.182.45.0 netmask 255.255.255.0 {
  range dynamic-bootp 10.182.45.92 10.182.45.100;
  option broadcast-address 10.182.45.255;
  option routers 10.182.45.1;
  next-server 10.182.77.133;
  filename = "pxelinux.0";
}

tftp配置

[root@xifenfei ~]# more /etc/xinetd.d/tftp
service tftp
{
        socket_type             = dgram
        protocol                = udp
        wait                    = yes
        user                    = root
        server                  = /usr/sbin/in.tftpd
        server_args             = -v -s /xd
        disable                 = no
        per_source              = 11
        cps                     = 100 2
        flags                   = IPv4
}

nfs配置

[root@xifenfei ~]# more /etc/exports
/xd *(no_root_squash,no_subtree_check,insecure)

pxe配置

[root@xifenfei ~]# cp /usr/share/syslinux/pxelinux.0 /xd

[root@xifenfei pxelinux.cfg]# more /xd/pxelinux.cfg/default 
default linux
timeout 70

label cell
prompt 1
display boot.msg
  kernel dl180/vmlinux-11.2.3.2.1-dl180-DL180
  append initrd=dl180/initrd-11.2.3.2.1-dl180-DL180.img pxe stit updfrm dhcp sk=192.168.30.90:/xd/dl180 preconf=192.168.30.90:/xd/prec
onf.csv

label db
prompt 1
display boot.msg
  kernel dl360/vmlinux-11.2.3.2.1-dl360-DL360
  append initrd=dl360/initrd-11.2.3.2.1-dl360-DL360.img pxe stit updfrm dhcp sk=192.168.30.90:/xd/dl360 preconf=192.168.30.90:/xd/prec
onf.csv

tar -pxvf the ImageMaker.tar
cd /xd/dl180
[root@xifenfei dl180]# ./makeImageMedia.sh -pxe -pxeout dl180
Please wait. Calculating md5 checksums for cellbits ...
Calculating md5 checksum for exaos.tbz ...
Calculating md5 checksum for cellboot.tbz ...
Calculating md5 checksum for cellfw.tbz ...
Calculating md5 checksum for kernel.tbz ...
Calculating md5 checksum for ofed.tbz ...
Calculating md5 checksum for sunutils.tbz ...
Calculating md5 checksum for hputils.tbz ...
Calculating md5 checksum for c7rpms.tbz ...
Calculating md5 checksum for commonos.tbz ...
Calculating md5 checksum for debugos.tbz ...
Calculating md5 checksum for cellrpms.tbz ...
Calculating md5 checksum for doclib.zip ...
Calculating md5 checksum for cell.bin ...
Store filename of nfsimg tarball nfsimg-11.2.3.2.1-dl180-DL180.tar inside initrd
Please wait. Making initrd ...
214836 blocks
Please wait. Calculating md5 checksums for boot ...
PXE NFS image:   /xd/dl180/./PXE/nfsimg-11.2.3.2.1-dl180-DL180.tar
PXE NFS md5 sum: /xd/dl180/./PXE/nfsimg-11.2.3.2.1-dl180-DL180.tar.md5
PXE initrd:      /xd/dl180/./PXE/initrd-11.2.3.2.1-dl180-DL180.img
PXE kernel:      /xd/dl180/./PXE/vmlinux-11.2.3.2.1-dl180-DL180

[root@xifenfei dl180]# mv /xd/dl180/./PXE/nfsimg-11.2.3.2.1-dl180-DL180.tar /xd/dl180/
[root@xifenfei dl180]# mv /xd/dl180/./PXE/nfsimg-11.2.3.2.1-dl180-DL180.tar.md5 /xd/dl180/
[root@xifenfei dl180]# mv /xd/dl180/./PXE/initrd-11.2.3.2.1-dl180-DL180.img /xd/dl180/
[root@xifenfei dl180]# mv /xd/dl180/./PXE/vmlinux-11.2.3.2.1-dl180-DL180 /xd/dl180/

[root@xifenfei dl180]# ll
total 1531612
drwxr-xr-x   3 root root       4096 Mar 26 23:41 boot
drwxrwxr-x   2 root root       4096 Jan  9 22:34 doc
drwxr-xr-x   2 root root       4096 Jan  9 22:33 grub
drwxr-xr-x  17 root root       4096 Mar 26 23:41 initrd
-rw-r--r--   1 root root   38839215 Mar 26 23:41 initrd-11.2.3.2.1-dl180-DL180.img
-rwxrwxr-x   1 root root      27485 Jan  9 22:34 makeImageMedia.sh
-rw-r--r--   1 root root 1524193280 Mar 26 23:40 nfsimg-11.2.3.2.1-dl180-DL180.tar
-rw-r--r--   1 root root         68 Mar 26 23:41 nfsimg-11.2.3.2.1-dl180-DL180.tar.md5
drwxrwxr-x   3 root root       4096 Jan  9 22:34 patches
drwxr-xr-x   2 root root       4096 Mar 26 23:48 PXE
-r-xr-xr-x   1 root root      39041 Mar 31  2011 README_FOR_FACTORY.txt
-r-xr-xr-x   1 root root    3688864 Mar 26 23:41 vmlinux-11.2.3.2.1-dl180-DL180

上传preconf.csv到/xd目录

[root@xifenfei xd]# ll preconf.csv 
-rw-r--r--  1 root root 2133 Mar 14 18:14 preconf.csv

然后重启dhcp,xinetd,nfs服务,重启需要恢复的xd的db and cell节点,验证结果如下

发表在 EXADATA | 2 条评论

ASM中磁盘组权限设置

发表于 2013 年 4 月 4 日 由 惜分飞

aix平台11gr2单库使用使用grid和oracle用户分别部署gi和db,在添加磁盘的时候，使用设置磁盘所属用户和组为grid与oinstall,设置权限为755.添加磁盘成功后，数据库直接crash.
asm添加磁盘操作

SQL>  alter diskgroup DATA add disk '/dev/rhdisk15' 
NOTE: Assigning number (2,7) to disk (/dev/rhdisk15)
NOTE: requesting all-instance membership refresh for group=2
NOTE: initializing header on grp 2 disk DATA_0007
NOTE: requesting all-instance disk validation for group=2
Wed Apr 03 22:09:03 2013
NOTE: skipping rediscovery for group 2/0xa026f7ec (DATA) on local instance.
NOTE: requesting all-instance disk validation for group=2
NOTE: skipping rediscovery for group 2/0xa026f7ec (DATA) on local instance.
NOTE: initiating PST update: grp = 2
Wed Apr 03 22:09:03 2013
GMON updating group 2 at 21 for pid 17, osid 22610284
NOTE: PST update grp = 2 completed successfully 
NOTE: membership refresh pending for group 2/0xa026f7ec (DATA)
GMON querying group 2 at 22 for pid 13, osid 20643916
NOTE: cache opening disk 7 of grp 2: DWDATAGRP_0007 path:/dev/rhdisk15
GMON querying group 2 at 23 for pid 13, osid 20643916
SUCCESS: refreshed membership for 2/0xa026f7ec (DATA)
NOTE: starting rebalance of group 2/0xa026f7ec (DATA) at power 1
SUCCESS:  alter diskgroup DATA add disk '/dev/rhdisk15'
Starting background process ARB0
Wed Apr 03 22:09:07 2013
ARB0 started with pid=22, OS id=14155890 
NOTE: assigning ARB0 to group 2/0xa026f7ec (DATA) with 1 parallel I/O
NOTE: Attempting voting file refresh on diskgroup DATA
Wed Apr 03 22:09:19 2013
SQL>  alter diskgroup DATA add disk '/dev/rhdisk11' 
Wed Apr 03 22:09:20 2013
NOTE: stopping process ARB0
NOTE: rebalance interrupted for group 2/0xa026f7ec (DATA)
NOTE: Assigning number (2,8) to disk (/dev/rhdisk11)
NOTE: requesting all-instance membership refresh for group=2
NOTE: initializing header on grp 2 disk DATA_0008
NOTE: requesting all-instance disk validation for group=2
NOTE: skipping rediscovery for group 2/0xa026f7ec (DATA) on local instance.
NOTE: requesting all-instance disk validation for group=2
NOTE: skipping rediscovery for group 2/0xa026f7ec (DATA) on local instance.
NOTE: initiating PST update: grp = 2
Wed Apr 03 22:09:23 2013
GMON updating group 2 at 24 for pid 17, osid 22610284
NOTE: PST update grp = 2 completed successfully 
NOTE: membership refresh pending for group 2/0xa026f7ec (DATA)
GMON querying group 2 at 25 for pid 13, osid 20643916
NOTE: cache opening disk 8 of grp 2: DATA_0008 path:/dev/rhdisk11
GMON querying group 2 at 26 for pid 13, osid 20643916
SUCCESS: refreshed membership for 2/0xa026f7ec (DATA)
NOTE: starting rebalance of group 2/0xa026f7ec (DATA) at power 1
SUCCESS:  alter diskgroup DATA add disk '/dev/rhdisk11'
Starting background process ARB0
Wed Apr 03 22:09:26 2013
ARB0 started with pid=22, OS id=22872116 
NOTE: assigning ARB0 to group 2/0xa026f7ec (DATA) with 1 parallel I/O
NOTE: Attempting voting file refresh on diskgroup DATA
Wed Apr 03 22:14:41 2013
NOTE: ASM client xifenfei:xifenfei disconnected unexpectedly.
NOTE: check client alert log.
NOTE: Trace records dumped in trace file /u01/diag/asm/+asm/+ASM/trace/+ASM_ora_15073468.trc
Wed Apr 03 22:16:53 2013
NOTE: client xifenfei:xifenfei registered, osid 20709378, mbr 0x0
Wed Apr 03 22:20:33 2013
NOTE: client xifenfei:xifenfei deregistered

这里可看到增加磁盘操作正常并且开始做rebalance，但是也看到关于client xifenfei异常断开连接(本质就是数据库crash)

crash时的alert日志

Wed Apr 03 22:00:00 2013
Setting Resource Manager plan SCHEDULER[0x318B]:DEFAULT_MAINTENANCE_PLAN via scheduler window
Setting Resource Manager plan DEFAULT_MAINTENANCE_PLAN via parameter
Wed Apr 03 22:00:00 2013
Starting background process VKRM
Wed Apr 03 22:00:00 2013
VKRM started with pid=31, OS id=22413426 
Wed Apr 03 22:09:06 2013
ORA-15025: could not open disk "/dev/rhdisk15"
ORA-27041: unable to open file
IBM AIX RISC System/6000 Error: 13: Permission denied
Additional information: 11
Wed Apr 03 22:09:06 2013
SUCCESS: disk DATA_0007 (7.2092304189) added to diskgroup DATA
Wed Apr 03 22:09:26 2013
ORA-15025: could not open disk "/dev/rhdisk15"
ORA-27041: unable to open file
IBM AIX RISC System/6000 Error: 13: Permission denied
Additional information: 11
Wed Apr 03 22:09:26 2013
SUCCESS: disk DATA_0008 (8.2092304190) added to diskgroup DATA
Wed Apr 03 22:14:40 2013
Errors in file /oracle/diag/rdbms/xifenfei/xifenfei/trace/xifenfei_dbw0_17367438.trc:
ORA-15080: synchronous I/O operation to a disk failed
WARNING: failed to write mirror side 1 of virtual extent 1 logical extent 0 of file 261 in 
group 2 on disk 7 allocation unit 464 
KCF: read, write or open error, block=0x6a online=1
        file=1 '+DATA/xifenfei/datafile/system.261.788373447'
        error=15081 txt: ''
Errors in file /oracle/diag/rdbms/xifenfei/xifenfei/trace/xifenfei_dbw0_17367438.trc:
Errors in file /oracle/diag/rdbms/xifenfei/xifenfei/trace/xifenfei_dbw0_17367438.trc:
ORA-63999: data file suffered media failure
ORA-01114: IO error writing block to file 1 (block # 106)
ORA-01110: data file 1: '+DATA/xifenfei/datafile/system.261.788373447'
ORA-15081: failed to submit an I/O operation to a disk
ORA-15081: failed to submit an I/O operation to a disk
DBW0 (ospid: 17367438): terminating the instance due to error 63999

这里可以看到数据库异常crash是因为/dev/rhdisk15没有权限去操作该文件，导致dbw0进程异常，从而出现该数据库crash

尝试重启数据库(asm重启正常)

SQL> startup
ORACLE instance started.

Total System Global Area 1.2827E+10 bytes
Fixed Size                  2233480 bytes
Variable Size            1711278968 bytes
Database Buffers         1.1073E+10 bytes
Redo Buffers               40894464 bytes
Database mounted.
ORA-01113: file 1 needs media recovery
ORA-01110: data file 1: '+DATA/xifenfei/datafile/system.261.788373447'

这里提示file 1需要恢复,查看alert日志,出现以下错误

Completed: ALTER DATABASE   MOUNT
Wed Apr 03 22:17:02 2013
ALTER DATABASE OPEN
Errors in file /oracle/diag/rdbms/xifenfei/xifenfei/trace/xifenfei_ora_11534798.trc:
ORA-27041: unable to open file
IBM AIX RISC System/6000 Error: 13: Permission denied
Additional information: 3
Additional information: 4
Additional information: 4194306
WARNING: Write Failed. group:2 disk:8 AU:462 offset:16384 size:16384
Errors in file /oracle/diag/rdbms/xifenfei/xifenfei/trace/xifenfei_ora_11534798.trc:
ORA-15080: synchronous I/O operation to a disk failed
WARNING: failed to write mirror side 1 of virtual extent 0 logical extent 0 of file 261 in 
group 2 on disk 8 allocation unit 462 
Errors in file /oracle/diag/rdbms/xifenfei/xifenfei/trace/xifenfei_ora_11534798.trc:
ORA-27041: unable to open file
IBM AIX RISC System/6000 Error: 13: Permission denied
Additional information: 3
Additional information: 4
Additional information: 4194306
WARNING: Write Failed. group:2 disk:8 AU:690 offset:16384 size:16384
Errors in file /oracle/diag/rdbms/xifenfei/xifenfei/trace/xifenfei_ora_11534798.trc:
ORA-27041: unable to open file
IBM AIX RISC System/6000 Error: 13: Permission denied
Additional information: 3
Additional information: 4
Additional information: 4194306
WARNING: Write Failed. group:2 disk:8 AU:918 offset:16384 size:16384
Errors in file /oracle/diag/rdbms/xifenfei/xifenfei/trace/xifenfei_ora_11534798.trc:
ORA-15080: synchronous I/O operation to a disk failed
WARNING: failed to write mirror side 1 of virtual extent 0 logical extent 0 of file 263 in 
group 2 on disk 8 allocation unit 918 
Errors in file /oracle/diag/rdbms/xifenfei/xifenfei/trace/xifenfei_ora_11534798.trc:
ORA-15080: synchronous I/O operation to a disk failed
WARNING: failed to write mirror side 1 of virtual extent 0 logical extent 0 of file 262 in 
group 2 on disk 8 allocation unit 690 
Errors in file /oracle/diag/rdbms/xifenfei/xifenfei/trace/xifenfei_ora_11534798.trc:
ORA-01110: data file 3: '+DATA/xifenfei/datafile/undotbs1.263.788373475'
ORA-01114: IO error writing block to file 3 (block # 1)
ORA-15081: failed to submit an I/O operation to a disk
ORA-15081: failed to submit an I/O operation to a disk
Errors in file /oracle/diag/rdbms/xifenfei/xifenfei/trace/xifenfei_ora_11534798.trc:
ORA-01110: data file 2: '+DATA/xifenfei/datafile/sysaux.262.788373463'
ORA-01114: IO error writing block to file 2 (block # 1)
ORA-15081: failed to submit an I/O operation to a disk
ORA-15081: failed to submit an I/O operation to a disk

recover database 操作

SQL> recover database;
ORA-00283: recovery session canceled due to errors
ORA-01201: file 1 header failed to write correctly

Wed Apr 03 22:18:49 2013
ALTER DATABASE RECOVER  database  
Media Recovery Start
 started logmerger process
Wed Apr 03 22:18:50 2013
Errors in file /oracle/diag/rdbms/xifenfei/xifenfei/trace/xifenfei_pr00_12714126.trc:
ORA-27041: unable to open file
IBM AIX RISC System/6000 Error: 13: Permission denied
Additional information: 3
Additional information: 4
Additional information: 4194306
WARNING: Write Failed. group:2 disk:8 AU:462 offset:16384 size:16384
Errors in file /oracle/diag/rdbms/xifenfei/xifenfei/trace/xifenfei_pr00_12714126.trc:
ORA-27041: unable to open file
IBM AIX RISC System/6000 Error: 13: Permission denied
Additional information: 3
Additional information: 4
Additional information: 4194306

依然是这里的提示依然是因为磁盘无读写权限从而出现数据库无法写数据文件问题,修改刚刚加入的磁盘文件权限问为660(4读2写1执行),表明与oinstall相同组的oracle用户对该磁盘也有读写权限.
这个事故是一个很简单,而且随着11g中asm使用grid和oracle用户的客户越来越多，相关的事故也越来越多，因为大多数使用人习惯直接给某个文件授权为755,而在这样的grid和oracle分开安装的系统中,将出现增加磁盘后,数据库crash,而且不能起来(因为oracle用户对磁盘只有读权限,无写权限),一种比较好的规范:在11gr2的asm系统中(grid和oracle用户),建议设置磁盘为grid.oinstall,权限设置为660

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