使用kfed运维兵器修复ASM磁盘和磁盘组

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关键词：ORA-15053、ORA-15027、ORA-15040、ORA-01187、kfed repair、kfed merge、kfed read、strace

数据库的ASM磁盘或ASM磁盘组不小心被人为误删除从而导致磁盘组无法挂载，DBA需要将磁盘组挂载起来。通过实验再次模拟故障环境，详细分解每个操作步骤，避免下次继续踩坑从而提升运维处置效率。

场景描述：假设ASM磁盘组被删除，我们将如何进行快速恢复呢？

模拟环境：两个节点的RAC集群、数据库名YWZD、ASM磁盘组名称YWZD、测试ASM磁盘名称YWZD1。

实验步骤：

1、查看ASM磁盘的名称、路径和状态信息；

col path for a50
set pagesize 100
set linesize 1000
select name,path,header_status from v$asm_disk 
where group_number = (select group_number from v$asm_diskgroup
where name='YWZD');-->输入ASM磁盘组名称
NAME                   PATH                          HEADER_STATU
------------------------------ -------------------------------------------------- ------------
YWZD_0000               /dev/oracleasm/disks/YWZD1              MEMBER
MEMBER表示ASM磁盘是磁盘组的成员。

2、创建测试表空间和测试表；

create tablespace ywzd datafile '+YWZD' size 100m;
create table ywzd as select * from dba_tables;
select count(*) from ywzd;COUNT(*)
----------1884

3、删除ASM磁盘组，会报ORA-15053错误，即磁盘组存在文件；

--删除ASM磁盘组
su - grid
$sqlplus / as sysasmSQL> drop diskgroup ywzd;
drop diskgroup ywzd
*
ERROR at line 1:
ORA-15039: diskgroup not dropped
ORA-15053: diskgroup "YWZD" contains existing files--错误码具体说明
$oerr ora 15053
15053, 00000, "diskgroup \"%s\" contains existing files"
// *Cause:  An attempt was made to drop a diskgroup that still contains
//          existing files.
// *Action: Specify the INCLUDING CONTENTS option to drop the diskgroup
//          and all of its existing files.
//

4、根据上述方案，再次删除ASM磁盘组并加INCLUDING CONTENTS参数。但是出现ORA-15027错误，即磁盘组被实例占用无法dismount。

--删除ASM磁盘组
SQL> drop diskgroup ywzd including contents;
drop diskgroup ywzd including contents
*
ERROR at line 1:
ORA-15039: diskgroup not dropped
ORA-15027: active use of diskgroup "YWZD" precludes its dismount--错误码具体说明
$oerr ora 15027
15027, 00000, "active use of diskgroup \"%s\" precludes its dismount"
// *Cause:  An ALTER DISKGROUP ... DISMOUNT command specified a diskgroup 
//          which had clients with open files in the diskgroup. Diskgroups 
//          cannot be dismounted until all open files in the diskgroup 
//          are closed. 
// *Action: Stop all clients that are using this diskgroup and retry 
//          the ALTER DISKGROUP ... DISMOUNT command.  Query the V$ASM_CLIENT
//          fixed view in an ASM instance or use ASMCMD LSOF to list active
//          clients.
//--查看占用磁盘组的实例名
select instance_name,db_name,status from GV$ASM_CLIENT 
where group_number = (select group_number from v$asm_diskgroup 
where name='YWZD');  -->>输入磁盘组名称
INSTANCE_NAME               DB_NAME    STATUS
------------------------------ -------- ------------
+ASM1                   ywzd CONNECTED
+ASM2                   ywzd CONNECTED--或者使用lsof命令查看
$asmcmd
ASMCMD> lsof
DB_Name   Instance_Name  Path                                                   ywzd  ywzd1      +YWZD/ywzd/DATAFILE/ywzd.257.1164789351            
ywzd  ywzd1      +YWZD/ywzd_block_track.log     

5、备份ASM磁盘头数据后，再执行删除，方便后面对比分析及恢复。

--备份磁盘头信息
kfed read /dev/oracleasm/disks/YWZD1        >/tmp/YWZD1-0-0-B  磁盘头信息备份
kfed read /dev/oracleasm/disks/YWZD1 blkn=1 >/tmp/YWZD1-0-1-B  对块号为1备份
kfed read /dev/oracleasm/disks/YWZD1 aun=1  >/tmp/YWZD1-1-0-B  对aun为1备份--关闭数据库实例
$srvctl stop database -d ywzd--切换到grid用户，先把其中一个节点的磁盘组DISMOUNT，否则会出现以下错误。
SQL> drop diskgroup ywzd including contents;
drop diskgroup ywzd including contents
*
ERROR at line 1:
ORA-15039: diskgroup not dropped
ORA-15073: diskgroup YWZD is mounted by another ASM instance--成功删除
SQL> drop diskgroup ywzd including contents;Diskgroup dropped.

6、手动再拉起磁盘组，出现ORA-15040错误，即磁盘组不完整错误。

--Mount磁盘组，提示磁盘组不完整
SQL> alter diskgroup ywzd mount;
alter diskgroup ywzd mount
*
ERROR at line 1:
ORA-15032: not all alterations performed
ORA-15017: diskgroup "YWZD" cannot be mounted
ORA-15040: diskgroup is incomplete--ASM实例日志，显示挂载失败
2024-03-28T12:44:58.456141+08:00
SQL> alter diskgroup ywzd mount 
2024-03-28T12:44:58.461584+08:00
NOTE: cache registered group YWZD 8/0x4C149EB9
NOTE: cache began mount (first) of group YWZD 8/0x4C149EB9
2024-03-28T12:44:58.518360+08:00
ERROR: no read quorum in group: required 2, found 0 disks
2024-03-28T12:44:58.518657+08:00
NOTE: cache dismounting (clean) group 8/0x4C149EB9 (YWZD)
NOTE: messaging CKPT to quiesce pins Unix process pid: 29396, image: oracle@hlw3-db11 (TNS V1-V3)
NOTE: dbwr not being msg'd to dismount
NOTE: LGWR not being messaged to dismount
NOTE: cache dismounted group 8/0x4C149EB9 (YWZD)
NOTE: cache ending mount (fail) of group YWZD number=8 incarn=0x4c149eb9
NOTE: cache deleting context for group YWZD 8/0x4c149eb9
2024-03-28T12:44:58.534982+08:00
GMON dismounting group 8 at 26996 for pid 34, osid 29396
2024-03-28T12:44:58.536694+08:00
ERROR: diskgroup YWZD was not mounted
ORA-15032: not all alterations performed
ORA-15017: diskgroup "YWZD" cannot be mounted
ORA-15040: diskgroup is incomplete2024-03-28T12:44:58.543094+08:00
ERROR: alter diskgroup ywzd mount--错误码具体信息
$oerr ora 15040
15040, 00000, "diskgroup is incomplete"
// *Cause:  Some of the disks comprising a diskgroup were not present.
// *Action: Check the hardware to ensure that all disks are functional. Also
//          check that the setting of the ASM_DISKSTRING initialization 
//          parameter has not changed.  Alternatively, for normal or high
//          redundancy diskgroups, use MOUNT FORCE to offline missing disks
//          as part of mounting the diskgroup.
//

7、使用fked再次备份下磁盘头数据，然后再进行删除前后对比。

--备份磁盘头数据
kfed read /dev/oracleasm/disks/YWZD1        >/tmp/YWZD1-0-0-A
kfed read /dev/oracleasm/disks/YWZD1 blkn=1 >/tmp/YWZD1-0-1-A
kfed read /dev/oracleasm/disks/YWZD1 aun=1  >/tmp/YWZD1-1-0-A--通过diff命令进行对比
diff /tmp/YWZD1-0-0-B /tmp/YWZD1-0-0-A

8、比较两个文件的差异信息，其中带有“!”符号的记录表示前后有差异。可以看到磁盘头状态从KFDHDR_MEMBER变成KFDHDR_FORMER。

命令一：$ diff -C 1 /tmp/YWZD1-0-0-B /tmp/YWZD1-0-0-A|grep "kfdhdb.hdrsts"
*** /tmp/YWZD1-0-0-B    2024-03-28 12:23:29.022209374 +0800
--- /tmp/YWZD1-0-0-A    2024-03-28 12:56:31.268409902 +0800
****************** 21,23 ****kfdhdb.grptyp:                        1 ; 0x026: KFDGTP_EXTERNAL
! kfdhdb.hdrsts:                        3 ; 0x027: KFDHDR_MEMBERkfdhdb.dskname:               YWZD_0000 ; 0x028: length=9
--- 21,23 ----kfdhdb.grptyp:                        1 ; 0x026: KFDGTP_EXTERNAL
! kfdhdb.hdrsts:                        4 ; 0x027: KFDHDR_FORMERkfdhdb.dskname:               YWZD_0000 ; 0x028: length=9
***************命令二：$diff -y /tmp/YWZD1-0-0-B /tmp/YWZD1-0-0-A|grep "|"
kfdhdb.hdrsts:                        3 ; 0x027: KFDHDR_MEMBE |    kfdhdb.hdrsts:                        4 ; 0x027: KFDHDR_FORME

9、核实上述的对比信息后，修改备份文件中的磁盘头状态参数kfdhdb.hdrsts，并将修改的内容合并到磁盘头。

--修改/tmp/YWZD1-0-0-A文件
kfdhdb.hdrsts:即状态值从4改为3，状态名称从KFDHDR_FORMER改为KFDHDR_MEMBER--合并修改结果
kfed merge /dev/oracleasm/disks/YWZD1 text=/tmp/YWZD1-0-0-A

10、最后把磁盘组挂载起来，并进行数据验证。

--核实磁盘状态是否为MEMBER
select name,path,header_status from v$asm_disk 
where group_number = (select group_number from v$asm_diskgroup
where name='YWZD');-->输入ASM磁盘组名称--挂载磁盘组
SQL> alter diskgroup ywzd mount;Diskgroup altered.--启动数据库，并验证数据
select count(*) from ywzd;

ASM磁盘组挂载成功！

实验证明：当磁盘组被误删除后，立即停止进一步损坏，可以通过kfed进行完美恢复。

场景描述：假设执行oracleasm deletedisks 命令删除ASM磁盘，我们将如何进行快速恢复呢？

模拟环境：两个节点的RAC集群、数据库名YWZD、ASM磁盘组名称YWZD、测试ASM磁盘名称YWZD1。

实验步骤：

1、确认数据文件状态信息；

--数据文件状态可用
col file_name for a60
set linesize 1000
select file_name ,status from dba_data_files where file_name like '+YWZD%';
FILE_NAME                             STATUS
------------------------------------------------------------ ---------
+YWZD/ywzd/DATAFILE/ywzd.257.1164789351             AVAILABLE--ASM磁盘可识别
$ oracleasm listdisks | grep YWZD
YWZD1

2、先备份ASM磁盘头数据，再执行删除ASM盘，方便后面对比分析或恢复使用。

--备份磁盘头信息
kfed read /dev/oracleasm/disks/YWZD1        >/tmp/YWZD11-0-0-B
kfed read /dev/oracleasm/disks/YWZD1 blkn=1 >/tmp/YWZD11-0-1-B
kfed read /dev/oracleasm/disks/YWZD1 aun=1  >/tmp/YWZD11-1-0-B

3、在节点1的root用户下执行deletedisk删除ASM磁盘

--删除磁盘
# oracleasm deletedisk YWZD1
Clearing disk header: done
Dropping disk: done# oracleasm listdisks | grep YWZD-->无记录# oracleasm scandisks
Reloading disk partitions: done
Cleaning any stale ASM disks...
Scanning system for ASM disks...

4、在节点2检查ASM的状态，磁盘状态从MEMBER变成为CANDIDATE。

--检查磁盘状态为CANDIDATE
col path for a40
col name for a20
set linesize 1000
select path,name,state ,header_status from v$asm_disk where path like '%YWZD%';
PATH                     NAME              STATE    HEADER_STATU
---------------------------------------- -------------------- -------- ------------
/dev/oracleasm/disks/YWZD1                      NORMAL   CANDIDATE--ASM磁盘扫描
# oracleasm scandisks
Reloading disk partitions: done
Cleaning any stale ASM disks...
Cleaning disk "YWZD1"
Scanning system for ASM disks...# oracleasm listdisks | grep YWZD-->无记录select path,name,state ,header_status from v$asm_disk where path like '%YWZD%'; no rows selected

5、检查数据库文件的状态，已经无法识别到数据文件。

--查看数据文件状态为AVAILABLE
col file_name for a60
select file_name ,status from dba_data_files where file_name like '+YWZD%'; 
FILE_NAME                             STATUS
------------------------------------------------------------ ---------
+YWZD/ywzd/DATAFILE/ywzd.257.1164789351             AVAILABLE--手动触发检查点
alter system checkpoint;
alter system checkpoint;--物理磁盘检测异常，触发磁盘组dismounted
select file_name ,status from dba_data_files where file_name like '+YWZD%'
*
ERROR at line 1:
ORA-01187: cannot read from file  because it failed verification tests
ORA-01110: data file 10: '+YWZD/ywzd/DATAFILE/ywzd.257.1164789351'--ASM日志
2024-03-28T22:21:01.941213+08:00
Errors in file /u01/app/oracle/diag/rdbms/ywzd/ywzd1/trace/ywzd1_ckpt_16646.trc:
ORA-01110: data file 10: '+YWZD/ywzd/DATAFILE/ywzd.257.1164789351'
ORA-01115: IO error reading block from file 10 (block # 1)
ORA-15078: ASM diskgroup was forcibly dismounted
ORA-15078: ASM diskgroup was forcibly dismounted

6、asm磁盘头的元数据在0号数据块，其备份的元数据在510号数据块，因此可以通过kfed repair来修复。

-- 执行修复命令触发KFED-00303
# su - grid
$ kfed repair /dev/oracleasm/disks/YWZD1
KFED-00303: unable to open file '/dev/oracleasm/disks/YWZD1'--通过命令把原先的ASM磁盘状态写入磁盘头（renamedisk -f）
$oracleasm createdisk YWZD1 /dev/mapper/YW-YWZD 
Unable to open device "/dev/mapper/YW-YWZD": Permission denied--root用户下创建
# oracleasm createdisk YWZD1 /dev/mapper/YW-YWZD
Writing disk header: done
Instantiating disk: done--检查ASM磁盘状态为PROVISIONEDPATH                     NAME              STATE    HEADER_STATU
---------------------------------------- -------------------- -------- ------------
/dev/oracleasm/disks/YWZD1                      NORMAL   PROVISIONED--再次执行kfed repair进行修复，并通过strace把日志记录下来。
strace -o asm_learn.log 
kfed repair /dev/oracleasm/disks/YWZD1--再次检查磁盘状态，已变成MEMBER
PATH                     NAME              STATE    HEADER_STATU
---------------------------------------- -------------------- -------- ------------
/dev/oracleasm/disks/YWZD1                      NORMAL   MEMBER--另一个节点扫描磁盘
# oracleasm scandisks
Reloading disk partitions: done
Cleaning any stale ASM disks...
Scanning system for ASM disks...
Instantiating disk "YWZD1"--手动挂载两个节点的磁盘组
SQL> select name,state from v$asm_diskgroup; NAME                   STATE
------------------------------ -----------
YWZD                   DISMOUNTEDSQL> alter diskgroup ywzd mount;Diskgroup altered.

7、检查数据文件状态及验证数据。

--数据文件读取异常
select file_name ,status from dba_data_files where file_name like '+YWZD%'
*
ERROR at line 1:
ORA-01187: cannot read from file  because it failed verification tests
ORA-01110: data file 10: '+YWZD/ywzd/DATAFILE/ywzd.257.1164789351'--错误码信息
!oerr ora 01187
01187, 00000, "cannot read from file %s because it failed verification tests"
// *Cause:  The data file did not pass the checks to insure it is part of the
//         database. Reads are not allowed until it is verified.
// *Action: Make the correct file available to the database. Then, either open
//         the database, or execute ALTER SYSTEM CHECK DATAFILES. --手动进行数据文件校验 
alter database datafile 10 online;Database altered.ALTER SYSTEM CHECK DATAFILES; Database altered.--数据文件状态恢复正常
select file_name ,status from dba_data_files where file_name like '+YWZD%';FILE_NAME                             STATUS
------------------------------------------------------------ ---------
+YWZD/ywzd/DATAFILE/ywzd.257.1164789351             AVAILABLE--数据成功恢复
SYS@ywzd1> select count(*) from ywzd;COUNT(*)
----------1884

根据以上步骤成功将ASM磁盘、ASM磁盘组和数据文件成功恢复出来。

虽然整个恢复过程步骤简单，但是还是要理解其中的原理。数据库底层未实际删除数据，而修改ASM磁盘头状态信息。可使用kfed工具手动调整磁盘头状态或将元数据备份直接恢复。

1、ASM磁盘头HEADER_STATUS的状态，常见有以下4种。

CANDIDATE\PROVISIONED：磁盘不是磁盘组的一部分，可以通过以下ALTER DISKGROUP语句添加到磁盘组中
MEMBER：磁盘是现有磁盘组的成员。请勿尝试将磁盘添加到其他磁盘组
FORMER：磁盘曾经是磁盘组的一部分，但已从该组中彻底删除。可以使用以下ALTER DISKGROUP语句将其添加到新的磁盘组中

2、正常情况下，可通过kfed read检查以下关键指标

kfbh.type 值为 KFBTYP_DISKHEAD
kfdhdb.hdrsts 值为 KFDHDR_MEMBER

• ASM tools used by Support : KFOD, KFED, AMDU (Doc ID 1485597.1)
• V$ASM_DISK_STAT和V$ASM_DISK_v$asm_disk字段说明-CSDN博客

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