disk_repair_time

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Oracle 10g引入了ASM，在10g版本中，如果由于故障(光缆故障，控制器故障，HBA卡故障或者其他故障造成磁盘无法访问)，这时Oracle会把这个磁盘drop掉。在11g中，Oracle引入了一个参数disk_repair_time，这个参数与"Oracle ASM Fast Mirror Resync"有关，有了这个特性，当故障发生时(除磁盘自身故障)，在disk_repair_time时间之内，待故障解决磁盘在线后，Oracle会同步由于故障而暂时没有写入本磁盘extent的数据，而不必同步磁盘上所有的数据，进而避免因此造成的性能问题。如果超过disk_repair_time时间，系统仍未修复，Oracle会drop这个磁盘。默认时间为3.6小时，一般能满足大多数环境，可以根据实际情况设置这个参数。

使用这个特性，要满足两个条件:

 1.磁盘组的COMPATIBLE属性版本至少在11.1及以上(磁盘组COMPATIBLE参数影响到磁盘组的格式，元数据，AU等)
 2.磁盘组的的冗余模式为Normal或High
 
注意：如果是磁盘自身故障(DG冗余模式为Norma/High)，这个磁盘必须drop，添加磁盘后，oracle会自动reblancing。如果冗余模式为external，磁盘出故障时，磁盘组会离线，要通过备份来恢复数据库。Exadata冗余度至少为Normal，是通过在ASM级别中mirror，所以等cell节点任何一个节点down机，不影响数据库的正常使用。

本文通过在11g ASM中创建一磁盘组db2，然后将磁盘组中一块盘offline，超过disk_repair_time后，观察磁盘的变化

ASMCMD> lsattr -G db2 -l

Name                     Value
access_control.enabled   FALSE
access_control.umask     066
au_size                  1048576
cell.smart_scan_capable  FALSE
compatible.asm           11.2.0.0.0
compatible.rdbms         10.1.0.0.0
disk_repair_time         3.6h
sector_size              512

ASMCMD> setattr -G db2 disk_repair_time 5h

ORA-15032: not all alterations perfORMed
ORA-15242: could not set attribute disk_repair_time
ORA-15283: ASM operation requires compatible.rdbms of 11.1.0.0.0 or higher (DBD ERROR: OCIStmtExecute)

注意：compatible参数至少为11.1

ASMCMD> setattr -G db2 compatible.rdbms 11.2
ASMCMD> lsattr -G db2 -l

Name                     Value
access_control.enabled   FALSE
access_control.umask     066
au_size                  1048576
cell.smart_scan_capable  FALSE
compatible.asm           11.2.0.0.0
compatible.rdbms         11.2
disk_repair_time         3.6h
sector_size              512

为了测试，设置disk_repair_time为5分钟，m代表分钟，h代表小时，如果不输单位，默认是小时

ASMCMD> setattr -G db2 disk_repair_time 5m
ASM alert后台日志

sql> ALTER DISKGROUP DB2 SET ATTRIBUTE 'disk_repair_time' = '5m'
SUCCESS: ALTER DISKGROUP DB2 SET ATTRIBUTE 'disk_repair_time' = '5m'

ASMCMD> lsattr -G db2 -l

Name                     Value
access_control.enabled   FALSE
access_control.umask     066
au_size                  1048576
cell.smart_scan_capable  FALSE
compatible.asm           11.2.0.0.0
compatible.rdbms         11.2
disk_repair_time         5m
sector_size              512
ASMCMD>

查看磁盘组的信息和磁盘头信息
ASMCMD> lsdsk -G db2

Path
/dev/oracleasm/disks/ASMDISK11
/dev/oracleasm/disks/ASMDISK13

ASMCMD> lsdsk -G db2 --statistics

Reads  Write  Read_Errs  Write_Errs  Read_time  Write_Time  Bytes_Read  Bytes_Written  Voting_File  Path
  191   1068          0           0    .965827    39.09044     1794048        4374528            N  /dev/oracleasm/disks/ASMDISK11
  166   1068          0           0   1.040196   38.521265      684032        4374528            N  /dev/oracleasm/disks/ASMDISK13

ASMCMD>
[oracle@ohs1 ~]$ kfed read /dev/oracleasm/disks/ASMDISK11

kfbh.endian:                          1 ; 0x000: 0x01
kfbh.hard:                          130 ; 0x001: 0x82
kfbh.type:                            1 ; 0x002: KFBTYP_DISKHEAD
kfbh.datfmt:                          1 ; 0x003: 0x01
kfbh.block.blk:                       0 ; 0x004: blk=0
kfbh.block.obj:              2147483648 ; 0x008: disk=0
kfbh.check:                  1549816565 ; 0x00c: 0x5c6052f5
kfbh.fcn.base:                        0 ; 0x010: 0x00000000
kfbh.fcn.wrap:                        0 ; 0x014: 0x00000000
kfbh.spare1:                          0 ; 0x018: 0x00000000
kfbh.spare2:                          0 ; 0x01c: 0x00000000
kfdhdb.driver.provstr:ORCLDISKASMDISK11 ; 0x000: length=17
kfdhdb.driver.reserved[0]:   1145918273 ; 0x008: 0x444d5341
kfdhdb.driver.reserved[1]:    827020105 ; 0x00c: 0x314b5349
kfdhdb.driver.reserved[2]:           49 ; 0x010: 0x00000031
kfdhdb.driver.reserved[3]:            0 ; 0x014: 0x00000000
kfdhdb.driver.reserved[4]:            0 ; 0x018: 0x00000000
kfdhdb.driver.reserved[5]:            0 ; 0x01c: 0x00000000
kfdhdb.compat:                186646528 ; 0x020: 0x0b200000
kfdhdb.dsknum:                        0 ; 0x024: 0x0000
kfdhdb.grptyp:                        2 ; 0x026: KFDGTP_NORMAL
kfdhdb.hdrsts:                        3 ; 0x027: KFDHDR_MEMBER
kfdhdb.dskname:                DB2_0000 ; 0x028: length=8
kfdhdb.grpname:                     DB2 ; 0x048: length=3
kfdhdb.fgname:                 DB2_0000 ; 0x068: length=8
kfdhdb.capname:                         ; 0x088: length=0
kfdhdb.crestmp.hi:             33036942 ; 0x0a8: HOUR=0xe DAYS=0x14 MNTH=0x6 YEAR=0x7e0
kfdhdb.crestmp.lo:           3147311104 ; 0x0ac: USEC=0x0 MSEC=0x20a SECS=0x39 MINS=0x2e
kfdhdb.mntstmp.hi:             33036942 ; 0x0b0: HOUR=0xe DAYS=0x14 MNTH=0x6 YEAR=0x7e0
kfdhdb.mntstmp.lo:           3163762688 ; 0x0b4: USEC=0x0 MSEC=0xcc SECS=0x9 MINS=0x2f
kfdhdb.secsize:                     512 ; 0x0b8: 0x0200
kfdhdb.blksize:                    4096 ; 0x0ba: 0x1000
kfdhdb.ausize:                  1048576 ; 0x0bc: 0x00100000
kfdhdb.mfact:                    113792 ; 0x0c0: 0x0001bc80
kfdhdb.dsksize:                    2447 ; 0x0c4: 0x0000098f
kfdhdb.pmcnt:                         2 ; 0x0c8: 0x00000002
kfdhdb.fstlocn:                       1 ; 0x0cc: 0x00000001
kfdhdb.altlocn:                       2 ; 0x0d0: 0x00000002
kfdhdb.f1b1locn:                      2 ; 0x0d4: 0x00000002
kfdhdb.redomirrors[0]:                0 ; 0x0d8: 0x0000
kfdhdb.redomirrors[1]:                0 ; 0x0da: 0x0000
kfdhdb.redomirrors[2]:                0 ; 0x0dc: 0x0000
kfdhdb.redomirrors[3]:                0 ; 0x0de: 0x0000
kfdhdb.dbcompat:              168820736 ; 0x0e0: 0x0a100000
kfdhdb.grpstmp.hi:             33036942 ; 0x0e4: HOUR=0xe DAYS=0x14 MNTH=0x6 YEAR=0x7e0
kfdhdb.grpstmp.lo:           3147119616 ; 0x0e8: USEC=0x0 MSEC=0x14f SECS=0x39 MINS=0x2e
kfdhdb.vfstart:                       0 ; 0x0ec: 0x00000000
kfdhdb.vfend:                         0 ; 0x0f0: 0x00000000
kfdhdb.spfile:                        0 ; 0x0f4: 0x00000000
kfdhdb.spfflg:                        0 ; 0x0f8: 0x00000000

[oracle@ohs1 ~]$ kfed read /dev/oracleasm/disks/ASMDISK13

kfbh.endian:                          1 ; 0x000: 0x01
kfbh.hard:                          130 ; 0x001: 0x82
kfbh.type:                            1 ; 0x002: KFBTYP_DISKHEAD
kfbh.datfmt:                          1 ; 0x003: 0x01
kfbh.block.blk:                       0 ; 0x004: blk=0
kfbh.block.obj:              2147483649 ; 0x008: disk=1
kfbh.check:                  1549816567 ; 0x00c: 0x5c6052f7
kfbh.fcn.base:                        0 ; 0x010: 0x00000000
kfbh.fcn.wrap:                        0 ; 0x014: 0x00000000
kfbh.spare1:                          0 ; 0x018: 0x00000000
kfbh.spare2:                          0 ; 0x01c: 0x00000000
kfdhdb.driver.provstr:ORCLDISKASMDISK13 ; 0x000: length=17
kfdhdb.driver.reserved[0]:   1145918273 ; 0x008: 0x444d5341
kfdhdb.driver.reserved[1]:    827020105 ; 0x00c: 0x314b5349
kfdhdb.driver.reserved[2]:           51 ; 0x010: 0x00000033
kfdhdb.driver.reserved[3]:            0 ; 0x014: 0x00000000
kfdhdb.driver.reserved[4]:            0 ; 0x018: 0x00000000
kfdhdb.driver.reserved[5]:            0 ; 0x01c: 0x00000000
kfdhdb.compat:                186646528 ; 0x020: 0x0b200000
kfdhdb.dsknum:                        1 ; 0x024: 0x0001
kfdhdb.grptyp:                        2 ; 0x026: KFDGTP_NORMAL
kfdhdb.hdrsts:                        3 ; 0x027: KFDHDR_MEMBER
kfdhdb.dskname:                DB2_0001 ; 0x028: length=8
kfdhdb.grpname:                     DB2 ; 0x048: length=3
kfdhdb.fgname:                 DB2_0001 ; 0x068: length=8
kfdhdb.capname:                         ; 0x088: length=0
kfdhdb.crestmp.hi:             33036942 ; 0x0a8: HOUR=0xe DAYS=0x14 MNTH=0x6 YEAR=0x7e0
kfdhdb.crestmp.lo:           3147311104 ; 0x0ac: USEC=0x0 MSEC=0x20a SECS=0x39 MINS=0x2e
kfdhdb.mntstmp.hi:             33036942 ; 0x0b0: HOUR=0xe DAYS=0x14 MNTH=0x6 YEAR=0x7e0
kfdhdb.mntstmp.lo:           3163762688 ; 0x0b4: USEC=0x0 MSEC=0xcc SECS=0x9 MINS=0x2f
kfdhdb.secsize:                     512 ; 0x0b8: 0x0200
kfdhdb.blksize:                    4096 ; 0x0ba: 0x1000
kfdhdb.ausize:                  1048576 ; 0x0bc: 0x00100000
kfdhdb.mfact:                    113792 ; 0x0c0: 0x0001bc80
kfdhdb.dsksize:                    2447 ; 0x0c4: 0x0000098f
kfdhdb.pmcnt:                         2 ; 0x0c8: 0x00000002
kfdhdb.fstlocn:                       1 ; 0x0cc: 0x00000001
kfdhdb.altlocn:                       2 ; 0x0d0: 0x00000002
kfdhdb.f1b1locn:                      2 ; 0x0d4: 0x00000002
kfdhdb.redomirrors[0]:                0 ; 0x0d8: 0x0000
kfdhdb.redomirrors[1]:                0 ; 0x0da: 0x0000
kfdhdb.redomirrors[2]:                0 ; 0x0dc: 0x0000
kfdhdb.redomirrors[3]:                0 ; 0x0de: 0x0000
kfdhdb.dbcompat:              168820736 ; 0x0e0: 0x0a100000
kfdhdb.grpstmp.hi:             33036942 ; 0x0e4: HOUR=0xe DAYS=0x14 MNTH=0x6 YEAR=0x7e0
kfdhdb.grpstmp.lo:           3147119616 ; 0x0e8: USEC=0x0 MSEC=0x14f SECS=0x39 MINS=0x2e
kfdhdb.vfstart:                       0 ; 0x0ec: 0x00000000
kfdhdb.vfend:                         0 ; 0x0f0: 0x00000000
kfdhdb.spfile:                        0 ; 0x0f4: 0x00000000
kfdhdb.spfflg:                        0 ; 0x0f8: 0x00000000

ASMCMD> iostat -G db2

Group_Name  Dsk_Name  Reads    Writes
DB2         DB2_0000  1859584  5001216
DB2         DB2_0001  749568   5001216

ASMCMD> offline -G db2 -D DB2_0001
Diskgroup altered.
ASMCMD>

从ASM alet中可以看到磁盘将要在5分钟后drop
WARNING: Disk 1 (DB2_0001) in group 1 will be dropped in: (300) secs on ASM inst 1
Mon Jun 20 15:55:23 2016

5分钟后，磁盘被ASM强制删除(alert日志)

SQL> alter diskgroup DB2 drop disk DB2_0001 force 
NOTE: GroupBlock outside rolling migration privileged region
NOTE: requesting all-instance membership refresh for group=1
Mon Jun 20 16:01:36 2016
GMON updating for reconfiguration, group 1 at 26 for pid 33, osid 8507
NOTE: cache closing disk 1 of grp 1: (not open) DB2_0001
NOTE: group DB2: updated PST location: disk 0000 (PST copy 0)
NOTE: group 1 PST updated.
Mon Jun 20 16:01:36 2016
NOTE: membership refresh pending for group 1/0xe0485f13 (DB2)
GMON querying group 1 at 27 for pid 19, osid 5801
NOTE: cache closing disk 1 of grp 1: (not open) _DROPPED_0001_DB2
SUCCESS: refreshed membership for 1/0xe0485f13 (DB2)
NOTE: starting rebalance of group 1/0xe0485f13 (DB2) at power 1
SUCCESS: alter diskgroup DB2 drop disk DB2_0001 force 
SUCCESS: PST-initiated drop disk in group 1(3762839315))
Starting background process ARB0
Mon Jun 20 16:01:39 2016
ARB0 started with pid=34, OS id=9355
NOTE: assigning ARB0 to group 1/0xe0485f13 (DB2) with 1 parallel I/O
NOTE: stopping process ARB0
SUCCESS: rebalance completed for group 1/0xe0485f13 (DB2)
NOTE: Attempting voting file refresh on diskgroup DB2
Mon Jun 20 16:01:43 2016
NOTE: GroupBlock outside rolling migration privileged region
NOTE: requesting all-instance membership refresh for group=1
GMON updating for reconfiguration, group 1 at 28 for pid 34, osid 9361
NOTE: cache closing disk 1 of grp 1: (not open) _DROPPED_0001_DB2
NOTE: group DB2: updated PST location: disk 0000 (PST copy 0)
NOTE: group 1 PST updated.
WARNING: offline disk number 1 has references (51 AUs)
NOTE: membership refresh pending for group 1/0xe0485f13 (DB2)
Mon Jun 20 16:01:49 2016
GMON querying group 1 at 29 for pid 19, osid 5801
NOTE: cache closing disk 1 of grp 1: (not open) _DROPPED_0001_DB2
Mon Jun 20 16:01:49 2016
SUCCESS: refreshed membership for 1/0xe0485f13 (DB2)
NOTE: Attempting voting file refresh on diskgroup DB2

可以看到磁盘组db2 offline_disks显示为1

ASMCMD> lsdg

State    Type    Rebal  Sector  Block       AU  Total_MB  Free_MB  Req_mir_free_MB  Usable_file_MB  Offline_disks  Voting_files  Name
MOUNTED  NORMAL  N         512   4096  1048576      2447     2394                0            1197              1             N  DB2/
MOUNTED  EXTERN  N         512   4096  1048576      4894     4786                0            4786              0             N  OHSDBA/
MOUNTED  NORMAL  N         512   4096  1048576      7341     6410             2447            1981              0             Y  SYSTEMDG/

ASMCMD> 

offline后，再次读取磁盘头部信息(发现头部信息没改变)

[oracle@ohs1 ~]$ kfed read /dev/oracleasm/disks/ASMDISK13

kfbh.endian:                          1 ; 0x000: 0x01
kfbh.hard:                          130 ; 0x001: 0x82
kfbh.type:                            1 ; 0x002: KFBTYP_DISKHEAD
kfbh.datfmt:                          1 ; 0x003: 0x01
kfbh.block.blk:                       0 ; 0x004: blk=0
kfbh.block.obj:              2147483649 ; 0x008: disk=1
kfbh.check:                  1549816567 ; 0x00c: 0x5c6052f7
kfbh.fcn.base:                        0 ; 0x010: 0x00000000
kfbh.fcn.wrap:                        0 ; 0x014: 0x00000000
kfbh.spare1:                          0 ; 0x018: 0x00000000
kfbh.spare2:                          0 ; 0x01c: 0x00000000
kfdhdb.driver.provstr:ORCLDISKASMDISK13 ; 0x000: length=17
kfdhdb.driver.reserved[0]:   1145918273 ; 0x008: 0x444d5341
kfdhdb.driver.reserved[1]:    827020105 ; 0x00c: 0x314b5349
kfdhdb.driver.reserved[2]:           51 ; 0x010: 0x00000033
kfdhdb.driver.reserved[3]:            0 ; 0x014: 0x00000000
kfdhdb.driver.reserved[4]:            0 ; 0x018: 0x00000000
kfdhdb.driver.reserved[5]:            0 ; 0x01c: 0x00000000
kfdhdb.compat:                186646528 ; 0x020: 0x0b200000
kfdhdb.dsknum:                        1 ; 0x024: 0x0001
kfdhdb.grptyp:                        2 ; 0x026: KFDGTP_NORMAL
kfdhdb.hdrsts:                        3 ; 0x027: KFDHDR_MEMBER
kfdhdb.dskname:                DB2_0001 ; 0x028: length=8
kfdhdb.grpname:                     DB2 ; 0x048: length=3
kfdhdb.fgname:                 DB2_0001 ; 0x068: length=8
kfdhdb.capname:                         ; 0x088: length=0
kfdhdb.crestmp.hi:             33036942 ; 0x0a8: HOUR=0xe DAYS=0x14 MNTH=0x6 YEAR=0x7e0
kfdhdb.crestmp.lo:           3147311104 ; 0x0ac: USEC=0x0 MSEC=0x20a SECS=0x39 MINS=0x2e
kfdhdb.mntstmp.hi:             33036942 ; 0x0b0: HOUR=0xe DAYS=0x14 MNTH=0x6 YEAR=0x7e0
kfdhdb.mntstmp.lo:           3163762688 ; 0x0b4: USEC=0x0 MSEC=0xcc SECS=0x9 MINS=0x2f
kfdhdb.secsize:                     512 ; 0x0b8: 0x0200
kfdhdb.blksize:                    4096 ; 0x0ba: 0x1000
kfdhdb.ausize:                  1048576 ; 0x0bc: 0x00100000
kfdhdb.mfact:                    113792 ; 0x0c0: 0x0001bc80
kfdhdb.dsksize:                    2447 ; 0x0c4: 0x0000098f
kfdhdb.pmcnt:                         2 ; 0x0c8: 0x00000002
kfdhdb.fstlocn:                       1 ; 0x0cc: 0x00000001
kfdhdb.altlocn:                       2 ; 0x0d0: 0x00000002
kfdhdb.f1b1locn:                      2 ; 0x0d4: 0x00000002
kfdhdb.redomirrors[0]:                0 ; 0x0d8: 0x0000
kfdhdb.redomirrors[1]:                0 ; 0x0da: 0x0000
kfdhdb.redomirrors[2]:                0 ; 0x0dc: 0x0000
kfdhdb.redomirrors[3]:                0 ; 0x0de: 0x0000
kfdhdb.dbcompat:              168820736 ; 0x0e0: 0x0a100000
kfdhdb.grpstmp.hi:             33036942 ; 0x0e4: HOUR=0xe DAYS=0x14 MNTH=0x6 YEAR=0x7e0
kfdhdb.grpstmp.lo:           3147119616 ; 0x0e8: USEC=0x0 MSEC=0x14f SECS=0x39 MINS=0x2e
kfdhdb.vfstart:                       0 ; 0x0ec: 0x00000000
kfdhdb.vfend:                         0 ; 0x0f0: 0x00000000
kfdhdb.spfile:                        0 ; 0x0f4: 0x00000000
kfdhdb.spfflg:                        0 ; 0x0f8: 0x00000000

SQL> select name, path from v$asm_disk;

NAME                                     PATH
---------------------------------------- ------------------------------------------------------------
                                         /dev/oracleasm/disks/ASMDISK14
                                         /dev/oracleasm/disks/ASMDISK13
_DROPPED_0001_DB2
DB2_0000                                 /dev/oracleasm/disks/ASMDISK11
OHSDBA_0001                              /dev/oracleasm/disks/ASMDISK10
OHSDBA_0000                              /dev/oracleasm/disks/ASMDISK9
DATA_PGoLD_0004                          /dev/oracleasm/disks/ASMDISK8
DATA_PGOLD_0003                          /dev/oracleasm/disks/ASMDISK7
DATA_PGOLD_0002                          /dev/oracleasm/disks/ASMDISK6
DATA_PGOLD_0001                          /dev/oracleasm/disks/ASMDISK5
DATA_PGOLD_0000                          /dev/oracleasm/disks/ASMDISK4

NAME                                     PATH
---------------------------------------- ------------------------------------------------------------
SYSTEMDG_0002                            /dev/oracleasm/disks/ASMDISK3
SYSTEMDG_0001                            /dev/oracleasm/disks/ASMDISK2
SYSTEMDG_0000                            /dev/oracleasm/disks/ASMDISK1

14 rows selected.
SQL>

被drop后，再次尝试online disk

ASMCMD>  online -G db2 -D DB2_0001

ORA-15032: not all alterations performed
ORA-15054: disk "DB2_0001" does not exist in diskgroup "DB2" (DBD ERROR: OCIStmtExecute)
ASMCMD>

尝试undrop disk，虽然没报什么错误，但是磁盘仍旧没能撤回成功

[oracle@ohs1 ~]$ sqlplus / as sysasm
SQL*Plus: Release 11.2.0.3.0 Production on Mon Jun 20 16:50:17 2016
Copyright (c) 1982, 2011, Oracle.  All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - Production
With the Real Application Clusters and Automatic Storage Management options

SQL> alter diskgroup db2 undrop disks;
Diskgroup altered.
SQL>

SQL> alter diskgroup db2 undrop disks
NOTE: GroupBlock outside rolling migration privileged region
NOTE: requesting all-instance membership refresh for group=2
Mon Jun 20 16:50:35 2016
GMON updating for reconfiguration, group 2 at 17 for pid 28, osid 16254
NOTE: cache closing disk 1 of grp 2: (not open) _DROPPED_0001_DB2
NOTE: group DB2: updated PST location: disk 0000 (PST copy 0)
NOTE: group 2 PST updated.
Mon Jun 20 16:50:36 2016
NOTE: membership refresh pending for group 2/0xfb327d85 (DB2)
GMON querying group 2 at 18 for pid 19, osid 13443
NOTE: cache closing disk 1 of grp 2: (not open) _DROPPED_0001_DB2
SUCCESS: refreshed membership for 2/0xfb327d85 (DB2)
NOTE: starting rebalance of group 2/0xfb327d85 (DB2) at power 1
SUCCESS: alter diskgroup db2 undrop disks
Starting background process ARB0
Mon Jun 20 16:50:38 2016
ARB0 started with pid=29, OS id=16331
NOTE: assigning ARB0 to group 2/0xfb327d85 (DB2) with 1 parallel I/O
NOTE: stopping process ARB0
SUCCESS: rebalance completed for group 2/0xfb327d85 (DB2)
NOTE: Attempting voting file refresh on diskgroup DB2
Mon Jun 20 16:50:41 2016
NOTE: GroupBlock outside rolling migration privileged region
NOTE: requesting all-instance membership refresh for group=2
GMON updating for reconfiguration, group 2 at 19 for pid 29, osid 16336
NOTE: cache closing disk 1 of grp 2: (not open) _DROPPED_0001_DB2
NOTE: group DB2: updated PST location: disk 0000 (PST copy 0)
NOTE: group 2 PST updated.
WARNING: offline disk number 1 has references (51 AUs)
NOTE: membership refresh pending for group 2/0xfb327d85 (DB2)
Mon Jun 20 16:50:48 2016
GMON querying group 2 at 20 for pid 19, osid 13443
NOTE: cache closing disk 1 of grp 2: (not open) _DROPPED_0001_DB2
Mon Jun 20 16:50:48 2016
SUCCESS: refreshed membership for 2/0xfb327d85 (DB2)
NOTE: Attempting voting file refresh on diskgroup DB2

ASMCMD> lsdg

State    Type    Rebal  Sector  Block       AU  Total_MB  Free_MB  Req_mir_free_MB  Usable_file_MB  Offline_disks  Voting_files  Name
MOUNTED  EXTERN  N         512   4096  1048576     12235    10514                0           10514              0             N  DATA_PGOLD/
MOUNTED  NORMAL  N         512   4096  1048576      2447     2394                0            1197              1             N  DB2/
MOUNTED  EXTERN  N         512   4096  1048576      4894     4786                0            4786              0             N  OHSDBA/
MOUNTED  NORMAL  N         512   4096  1048576      7341     6410             2447            1981              0             Y  SYSTEMDG/

ASMCMD>

NAME                           PATH
------------------------------ ------------------------------------------------------------
                               /dev/oracleasm/disks/ASMDISK14
                               /dev/oracleasm/disks/ASMDISK13
_DROPPED_0001_DB2
DB2_0000                       /dev/oracleasm/disks/ASMDISK11
OHSDBA_0001                    /dev/oracleasm/disks/ASMDISK10
OHSDBA_0000                    /dev/oracleasm/disks/ASMDISK9
DATA_PGOLD_0004                /dev/oracleasm/disks/ASMDISK8
DATA_PGOLD_0003                /dev/oracleasm/disks/ASMDISK7
DATA_PGOLD_0002                /dev/oracleasm/disks/ASMDISK6
DATA_PGOLD_0001                /dev/oracleasm/disks/ASMDISK5
DATA_PGOLD_0000                /dev/oracleasm/disks/ASMDISK4

NAME                           PATH
------------------------------ ------------------------------------------------------------
SYSTEMDG_0002                  /dev/oracleasm/disks/ASMDISK3
SYSTEMDG_0001                  /dev/oracleasm/disks/ASMDISK2
SYSTEMDG_0000                  /dev/oracleasm/disks/ASMDISK1

14 rows selected.
SQL>

因为offline被drop后，磁盘头部信息并未改变，所以再次添加原来的磁盘时出现错误

SQL> alter diskgroup db2 add disk '/dev/oracleasm/disks/ASMDISK13';

alter diskgroup db2 add disk '/dev/oracleasm/disks/ASMDISK13'
*
ERROR at line 1:
ORA-15032: not all alterations performed
ORA-15033: disk '/dev/oracleasm/disks/ASMDISK13' belongs to diskgroup "DB2"

SQL>

清除ASM磁盘头部信息，重新添加磁盘

[oracle@ohs1 ~]$ dd if=/dev/zero of=/dev/oracleasm/disks/ASMDISK13 bs=1024 count=1

1+0 records in
1+0 records out
1024 bytes (1.0 kB) copied, 0.00966501 seconds, 106 kB/s

[oracle@ohs1 ~]$ kfed read /dev/oracleasm/disks/ASMDISK13

kfbh.endian:                          0 ; 0x000: 0x00
kfbh.hard:                            0 ; 0x001: 0x00
kfbh.type:                            0 ; 0x002: KFBTYP_INVALID
kfbh.datfmt:                          0 ; 0x003: 0x00
kfbh.block.blk:                       0 ; 0x004: blk=0
kfbh.block.obj:                       0 ; 0x008: file=0
kfbh.check:                           0 ; 0x00c: 0x00000000
kfbh.fcn.base:                        0 ; 0x010: 0x00000000
kfbh.fcn.wrap:                        0 ; 0x014: 0x00000000
kfbh.spare1:                          0 ; 0x018: 0x00000000
kfbh.spare2:                          0 ; 0x01c: 0x00000000
B7F60200 00000000 00000000 00000000 00000000  [................]
  Repeat 255 times
KFED-00322: Invalid content encountered during block traversal: [kfbtTraverseBlock][Invalid OSM block type][][0]

[oracle@ohs1 ~]$ sqlplus / as sysasm

SQL*Plus: Release 11.2.0.3.0 Production on Mon Jun 20 17:13:37 2016
Copyright (c) 1982, 2011, Oracle.  All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - Production
With the Real Application Clusters and Automatic Storage Management options

SQL> alter diskgroup db2 add disk '/dev/oracleasm/disks/ASMDISK13';
Diskgroup altered.
SQL>

注意：磁盘被drop后，磁盘头部没有变化，如果磁盘本身没有问题，还想再利用这个盘，必须清除磁盘头部才能重新添加。

Reference
Oracle ASM Fast Mirror Resync
http://docs.oracle.com/cd/E11882_01/server.112/e18951/asmdiskgrps.htm#OSTMG10044
disk group attribute

http://docs.oracle.com/cd/E11882_01/server.112/e18951/asmdiskgrps.htm#OSTMG10045

http://docs.oracle.com/cd/E11882_01/server.112/e18951/asmdiskgrps.htm#OSTMG137

http://docs.oracle.com/database/121/OSTMG/GUID-7A52077C-DCE5-44E0-BFA9-D30F485B8079.htm#GUID-1E46D1B6-F0A6-444D-A222-995069BCEF2F

http://docs.oracle.com/database/121/HABPT/config_storage.htm#HABPT4813

======================================================================
http://www.oratea.com/2017/05/19/disk_repair_time%E4%BB%8B%E7%BB%8D/

DISK_REPAIR_TIME介绍

1. 介绍
当ASM磁盘被drop后，ASM就会发起重平衡，保证被drop的磁盘里涉及的extent再次冗余，但是ASM的重平衡很费时间，并且涉及到大量其它磁盘的IO操作。但是有时侯磁盘可能会因为维护或其它原因暂时offline了，如果短时间的offline就发生重平衡，并且磁盘加回来时，又要发生重平衡，这有点不可接受。所以ASM提供了快速磁盘同步特性，在磁盘OFFLINE期间，ASM记录OFFLINE磁盘涉及的extent，而当磁盘恢复时，ASM会快速同步这个磁盘上发生变化的extent。
如果磁盘OFFLINE很长时间，这其实是有风险的，因为在NORMAL冗余的情况下，OFFLINE磁盘涉及的extent就只有一份了，所以ASM提供了一个磁盘组属性DISK_REPAIR_NAME，表明在这个磁盘组上的磁盘，OFFLINE多长时间后就被DROP，ASM开始重平衡，这个值默认是3.6小时。
如果是有计划磁盘OFFLINE维护，3.6小时也许不够，比如Exadata的Cell节点升级，所以可能需要先将该值调大。

--在磁盘组正常情况下，设置该值的命令如下：
    
SQL> ALTER DISKGROUP DATA SET ATTRIBUTE 'disk_repair_time'= '36h';

但是如果磁盘已经被offline，那如何设置offline的磁盘多长时间drop呢？命令有些不同。


2. 判断多少时间后磁盘被drop
--在ASM的alert日志里查看，磁盘被drop掉之前的倒计时，如下：

WARNING: Disk 0 (DATA_CD_00_DMORLCEL08) in group 1 will be dropped in: (12960) secs on ASM inst 1
WARNING: Disk 1 (DATA_CD_01_DMORLCEL08) in group 1 will be dropped in: (12960) secs on ASM inst 1
WARNING: Disk 2 (DATA_CD_02_DMORLCEL08) in group 1 will be dropped in: (12960) secs on ASM inst 1

--检查DISK_REPAIR_NAME
SQL> column name format a30
SQL> column value format a30
SQL> select name,value from v$asm_attribute where group_number=1 and name like '%disk_repair_time%';
 
NAME                           VALUE
------------------------------ ------------------------------
disk_repair_time               3.6h


3. 延长DISK_REPAIR_TIME
--如果一个failgroup失败，failgroup上的磁盘已经全部OFFLINE了，可以使用如下命令延长DISK_REPAIR_TIME
    
SQL> ALTER DISKGROUP <DISKGROUP NAME> OFFLINE DISKS IN FAILGROUP <FAILGROUP NAME> DROP AFTER 5H;

--然后再检查ASM的alert日志，是否生效，例如：
    
WARNING: Disk 2 (DATA_CD_02_DMORLCEL08) in group 1 will be dropped in: (18000) secs on ASM inst 1
WARNING: Disk 3 (DATA_CD_03_DMORLCEL08) in group 1 will be dropped in: (18000) secs on ASM inst 1
WARNING: Disk 4 (DATA_CD_04_DMORLCEL08) in group 1 will be dropped in: (18000) secs on ASM inst 1
WARNING: Disk 5 (DATA_CD_05_DMORLCEL08) in group 1 will be dropped in: (18000) secs on ASM inst 1

--如果只有1块盘offline，命令如下：
    
SQL> ALTER DISKGROUP <DISKGROUP NAME> OFFLINE DISK <DISK NAME> DROP AFTER 5H;

--检查磁盘名称
SQL> col path format a59
SQL> set lines 200
SQL> set pagesi 400
SQL> select path, name, header_status, mode_status, mount_status, state, failgroup from v$asm_disk order by path;


4. 立即drop磁盘
--如果磁盘的修复时间预计比较长，那可以立即drop掉磁盘，开始重平衡，而不是等完DISK_REPAIR_TIME时间后再开始。

如果failgroup失败，命令如下：
    
ALTER DISKGROUP <DISKGROUP NAME> DROP DISKS IN FAILGROUP <FAILGROUP NAME> FORCE;

如果某块磁盘失败，命令如下：
    
ALTER DISKGROUP <DISKGROUP NAME> DROP DISK <DISK NAME> FORCE;