start_udev 是不是会写磁盘头

遇到一个案例，在这里记录一下

一套Oracle 11.2.0.4 RAC环境，操作系统是RHEL 6.5，共享磁盘是通过UDEV实现RAW绑定设备名，如下

[root@rac1 opt]# ll /dev/sd*
brw-rw----. 1 root disk 8,  0 Dec  2 20:26 /dev/sda
brw-rw----. 1 root disk 8,  1 Dec  2 20:26 /dev/sda1
brw-rw----. 1 root disk 8,  2 Dec  2 20:26 /dev/sda2
brw-rw----. 1 root disk 8, 16 Dec  2 20:26 /dev/sdb
brw-rw----. 1 root disk 8, 17 Dec  2 20:26 /dev/sdb1
brw-rw----. 1 root disk 8, 32 Dec  2 20:26 /dev/sdc
brw-rw----. 1 root disk 8, 33 Dec  2 20:26 /dev/sdc1
brw-rw----. 1 root disk 8, 48 Dec  2 20:26 /dev/sdd
brw-rw----. 1 root disk 8, 49 Dec  2 20:26 /dev/sdd1
brw-rw----. 1 root disk 8, 64 Dec  2 20:26 /dev/sde
brw-rw----. 1 root disk 8, 65 Dec  2 20:26 /dev/sde1  
             
[root@rac1 opt]# cat /etc/udev/rules.d/60-raw.rules 
# Enter raw device bindings here.
#
# An example would be:
#   ACTION=="add", KERNEL=="sda", RUN+="/bin/raw /dev/raw/raw1 %N"
# to bind /dev/raw/raw1 to /dev/sda, or
#   ACTION=="add", ENV{MAJOR}=="8", ENV{MINOR}=="1", RUN+="/bin/raw /dev/raw/raw2 %M %m"
# to bind /dev/raw/raw2 to the device with major 8, minor 1.

ACTION=="add",KERNEL=="/dev/sdb1",RUN+='/bin/raw /dev/raw/raw1 %N"
ACTION=="add",ENV{MAJOR}=="8",ENV{MINOR}=="17",RUN+="/bin/raw /dev/raw/raw1 %M %m"
ACTION=="add",KERNEL=="/dev/sdc1",RUN+='/bin/raw /dev/raw/raw2 %N"
ACTION=="add",ENV{MAJOR}=="8",ENV{MINOR}=="33",RUN+="/bin/raw /dev/raw/raw2 %M %m"
ACTION=="add",KERNEL=="/dev/sdd1",RUN+='/bin/raw /dev/raw/raw3 %N"
ACTION=="add",ENV{MAJOR}=="8",ENV{MINOR}=="49",RUN+="/bin/raw /dev/raw/raw3 %M %m"
ACTION=="add",KERNEL=="/dev/sde1",RUN+='/bin/raw /dev/raw/raw4 %N"
ACTION=="add",ENV{MAJOR}=="8",ENV{MINOR}=="65",RUN+="/bin/raw /dev/raw/raw4 %M %m"
KERNEL=="raw[1-4]",OWNER="grid",GROUP="asmadmin",MODE="660"

[root@rac1 opt]# ll /dev/raw
total 0
crw-rw----. 1 grid asmadmin 162, 1 Dec  2 21:09 raw1
crw-rw----. 1 grid asmadmin 162, 2 Dec  2 21:09 raw2
crw-rw----. 1 grid asmadmin 162, 3 Dec  2 21:09 raw3
crw-rw----. 1 grid asmadmin 162, 4 Dec  2 20:26 raw4
crw-rw----. 1 root disk     162, 0 Dec  2 20:26 rawctl

一天，由于磁盘出现IO问题，导致RAC经常重启，存储修复磁盘切换了存储链路，导致映射到OS上的存储设备名发生了改变，导致UDEV绑定失败

下面修改UDEV的绑定方式，通过UUID绑定磁盘，如下

[root@rac1 ~]# for i in `cat /proc/partitions | awk '{print $4}' |grep sd | grep [a-z]$`; do echo "### $i: `scsi_id -g -u  -d  /dev/$i`"; done
### sda: 1ATA_VBOX_HARDDISK_VB85d0d4ba-e17b3dda
### sdb: 1ATA_VBOX_HARDDISK_VBc325912a-0addf096
### sdc: 1ATA_VBOX_HARDDISK_VB03a27735-42af5dea
### sdd: 1ATA_VBOX_HARDDISK_VB207dd3a2-a2f610c4
### sde: 1ATA_VBOX_HARDDISK_VBbc4b578d-a8e62d78

vi /etc/udev/rules.d/99-asm-oracle.rules
ACTION=="add",BUS=="scsi", KERNEL=="sd*", PROGRAM=="/sbin/scsi_id --whitelisted --replace-whitespace --device=/dev/$name", RESULT=="1ATA_VBOX_HARDDISK_VBc325912a-0addf096", RUN+="/bin/raw /dev/raw/raw1 %N"
ACTION=="add",BUS=="scsi", KERNEL=="sd*", PROGRAM=="/sbin/scsi_id --whitelisted --replace-whitespace --device=/dev/$name", RESULT=="1ATA_VBOX_HARDDISK_VB03a27735-42af5dea", RUN+="/bin/raw /dev/raw/raw2 %N"
ACTION=="add",BUS=="scsi", KERNEL=="sd*", PROGRAM=="/sbin/scsi_id --whitelisted --replace-whitespace --device=/dev/$name", RESULT=="1ATA_VBOX_HARDDISK_VB207dd3a2-a2f610c4", RUN+="/bin/raw /dev/raw/raw3 %N"
ACTION=="add",BUS=="scsi", KERNEL=="sd*", PROGRAM=="/sbin/scsi_id --whitelisted --replace-whitespace --device=/dev/$name", RESULT=="1ATA_VBOX_HARDDISK_VBbc4b578d-a8e62d78", RUN+="/bin/raw /dev/raw/raw4 %N"
KERNEL=="raw[1-4]",OWNER="grid",GROUP="asmadmin",MODE="0660"

删除 /etc/udev/rules.d/60-raw.rules 文件的绑定方式，关闭了所有节点的CRS，重新启动UDEV 

[root@rac1 ~]# /u01/app/11.2.0/grid/bin/crsctl stop crs
[root@rac2 ~]# /u01/app/11.2.0/grid/bin/crsctl stop crs
[root@rac1 ~]# start_udev

启动CRS，发现CRS识别不到表决磁盘，crs alter报错信息如下

[root@rac1 rac1]# tail -f alertrac1.log 

[ohasd(5337)]CRS-2767:Resource state recovery not attempted for 'ora.diskmon' as its target state is OFFLINE
2019-12-02 21:20:40.230: 
[ohasd(5337)]CRS-2769:Unable to failover resource 'ora.diskmon'.
2019-12-02 21:20:42.580: 
[cssd(6272)]CRS-1714:Unable to discover any voting files, retrying discovery in 15 seconds; Details at (:CSSNM00070:) in /u01/app/11.2.0/grid/log/rac1/cssd/ocssd.log
2019-12-02 21:20:57.605: 
[cssd(6272)]CRS-1714:Unable to discover any voting files, retrying discovery in 15 seconds; Details at (:CSSNM00070:) in /u01/app/11.2.0/grid/log/rac1/cssd/ocssd.log

ocssd.log的报错信息如下：

[root@rac1 ~]# tail -f /u01/app/11.2.0/grid/log/rac1/cssd/ocssd.log

2019-12-02 21:21:27.636: [   SKGFD][411584256]Execute glob on the string /dev/raw/*
2019-12-02 21:21:27.636: [   SKGFD][411584256]running stat on disk:/dev/raw/raw1
2019-12-02 21:21:27.636: [   SKGFD][411584256]running stat on disk:/dev/raw/raw3
2019-12-02 21:21:27.636: [   SKGFD][411584256]running stat on disk:/dev/raw/raw2
2019-12-02 21:21:27.636: [   SKGFD][411584256]running stat on disk:/dev/raw/raw4
2019-12-02 21:21:27.636: [   SKGFD][411584256]running stat on disk:/dev/raw/rawctl
2019-12-02 21:21:27.636: [   SKGFD][411584256]Fetching UFS disk :/dev/raw/rawctl:

2019-12-02 21:21:27.637: [   SKGFD][411584256]Fetching UFS disk :/dev/raw/raw4:

2019-12-02 21:21:27.637: [   SKGFD][411584256]Fetching UFS disk :/dev/raw/raw2:

2019-12-02 21:21:27.637: [   SKGFD][411584256]Fetching UFS disk :/dev/raw/raw3:

2019-12-02 21:21:27.637: [   SKGFD][411584256]Fetching UFS disk :/dev/raw/raw1:

2019-12-02 21:21:27.637: [   SKGFD][411584256]OSS discovery with ::

2019-12-02 21:21:27.638: [   SKGFD][411584256]Handle 0x7f8704140a50 from lib :UFS:: for disk :/dev/raw/raw4:

2019-12-02 21:21:27.638: [   SKGFD][411584256]Handle 0x7f8704138d60 from lib :UFS:: for disk :/dev/raw/raw2:

2019-12-02 21:21:27.638: [   SKGFD][411584256]Handle 0x7f8704139590 from lib :UFS:: for disk :/dev/raw/raw3:

2019-12-02 21:21:27.638: [   SKGFD][411584256]Handle 0x7f8704141e40 from lib :UFS:: for disk :/dev/raw/raw1:

2019-12-02 21:21:27.639: [   SKGFD][411584256]Lib :UFS:: closing handle 0x7f8704140a50 for disk :/dev/raw/raw4:

2019-12-02 21:21:27.639: [   SKGFD][411584256]Lib :UFS:: closing handle 0x7f8704138d60 for disk :/dev/raw/raw2:

2019-12-02 21:21:27.639: [   SKGFD][411584256]Lib :UFS:: closing handle 0x7f8704139590 for disk :/dev/raw/raw3:

2019-12-02 21:21:27.639: [   SKGFD][411584256]Lib :UFS:: closing handle 0x7f8704141e40 for disk :/dev/raw/raw1:

2019-12-02 21:21:27.639: [    CSSD][411584256]clssnmvDiskVerify: Successful discovery of 0 disks
2019-12-02 21:21:27.639: [    CSSD][411584256]clssnmCompleteInitVFDiscovery: Completing initial voting file discovery
2019-12-02 21:21:27.639: [    CSSD][411584256]clssnmvFindInitialConfigs: No voting files found
2019-12-02 21:21:27.639: [    CSSD][411584256](:CSSNM00070:)clssnmCompleteInitVFDiscovery: Voting file not found. Retrying discovery in 15 seconds
2019-12-02 21:21:27.766: [    CSSD][414275328]clssscSelect: cookie accept request 0x7f8710083a90
2019-12-02 21:21:27.766: [    CSSD][414275328]clssscevtypSHRCON: getting client with cmproc 0x7f8710083a90
2019-12-02 21:21:27.766: [    CSSD][414275328]clssgmRegisterClient: proc(5/0x7f8710083a90), client(40/0x7f8710063d30)
2019-12-02 21:21:27.766: [    CSSD][414275328]clssgmExecuteClientRequest(): type(6) size(684) only connect and exit messages are allowed before lease acquisition proc(0x7f8710083a90) client(0x7f8710063d30)
2019-12-02 21:21:27.766: [    CSSD][414275328]clssgmDiscEndpcl: gipcDestroy 0xdcc
2019-12-02 21:21:28.521: [    CSSD][414275328]clssscSelect: cookie accept request 0x7f871006f0b0
2019-12-02 21:21:28.521: [    CSSD][414275328]clssscevtypSHRCON: getting client with cmproc 0x7f871006f0b0
2019-12-02 21:21:28.521: [    CSSD][414275328]clssgmRegisterClient: proc(3/0x7f871006f0b0), client(42/0x7f8710063d30)
2019-12-02 21:21:28.521: [    CSSD][414275328]clssgmExecuteClientRequest(): type(6) size(684) only connect and exit messages are allowed before lease acquisition proc(0x7f871006f0b0) client(0x7f8710063d30)
2019-12-02 21:21:28.521: [    CSSD][414275328]clssgmDiscEndpcl: gipcDestroy 0xde2
2019-12-02 21:21:28.767: [    CSSD][414275328]clssscSelect: cookie accept request 0x7f8710083a90
2019-12-02 21:21:28.767: [    CSSD][414275328]clssscevtypSHRCON: getting client with cmproc 0x7f8710083a90
2019-12-02 21:21:28.767: [    CSSD][414275328]clssgmRegisterClient: proc(5/0x7f8710083a90), client(41/0x7f8710096260)
2019-12-02 21:21:28.767: [    CSSD][414275328]clssgmExecuteClientRequest(): type(6) size(684) only connect and exit messages are allowed before lease acquisition proc(0x7f8710083a90) client(0x7f8710096260)
2019-12-02 21:21:28.767: [    CSSD][414275328]clssgmDiscEndpcl: gipcDestroy 0xdf8

rac1:/home/grid$ kfod asm_diskstring='/dev/raw/*' disks=all
--------------------------------------------------------------------------------
 Disk          Size Path                                     User     Group   
================================================================================
   1:       1019 Mb /dev/raw/raw1                            grid     asmadmin
   2:       1019 Mb /dev/raw/raw2                            grid     asmadmin
   3:       1019 Mb /dev/raw/raw3                            grid     asmadmin
   4:       8189 Mb /dev/raw/raw4                            grid     asmadmin
KFOD-00301: Unable to contact Cluster Synchronization Services (CSS). Return code 2 from kgxgncin.
KFOD-00311: Error scanning device /dev/raw/rawctl
ORA-15025: could not open disk "/dev/raw/rawctl"
Linux-x86_64 Error: 13: Permission denied
Additional information: 42

rac1:/home/grid$ kfed read /dev/raw/raw1
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
7FCB36A16400 00000000 00000000 00000000 00000000  [................]
        Repeat 26 times
7FCB36A165B0 00000000 00000000 BB43868B 01000000  [..........C.....]
7FCB36A165C0 FE830001 003F813F DDC30000 0000001F  [....?.?.........]
7FCB36A165D0 00000000 00000000 00000000 00000000  [................]
        Repeat 1 times
7FCB36A165F0 00000000 00000000 00000000 AA550000  [..............U.]
7FCB36A16600 00000000 00000000 00000000 00000000  [................]
  Repeat 223 times
KFED-00322: Invalid content encountered during block traversal: [kfbtTraverseBlock][Invalid OSM block type][][0]

将UDEV的绑定方式从绑定设备的UUID改回原来的绑定设备名，start_udev，磁盘恢复正常，集群启动成功。

[root@rac1 opt]# cat /etc/udev/rules.d/60-raw.rules 
# Enter raw device bindings here.
#
# An example would be:
#   ACTION=="add", KERNEL=="sda", RUN+="/bin/raw /dev/raw/raw1 %N"
# to bind /dev/raw/raw1 to /dev/sda, or
#   ACTION=="add", ENV{MAJOR}=="8", ENV{MINOR}=="1", RUN+="/bin/raw /dev/raw/raw2 %M %m"
# to bind /dev/raw/raw2 to the device with major 8, minor 1.

ACTION=="add",KERNEL=="/dev/sdb1",RUN+='/bin/raw /dev/raw/raw1 %N"
ACTION=="add",ENV{MAJOR}=="8",ENV{MINOR}=="17",RUN+="/bin/raw /dev/raw/raw1 %M %m"
ACTION=="add",KERNEL=="/dev/sdc1",RUN+='/bin/raw /dev/raw/raw2 %N"
ACTION=="add",ENV{MAJOR}=="8",ENV{MINOR}=="33",RUN+="/bin/raw /dev/raw/raw2 %M %m"
ACTION=="add",KERNEL=="/dev/sdd1",RUN+='/bin/raw /dev/raw/raw3 %N"
ACTION=="add",ENV{MAJOR}=="8",ENV{MINOR}=="49",RUN+="/bin/raw /dev/raw/raw3 %M %m"
ACTION=="add",KERNEL=="/dev/sde1",RUN+='/bin/raw /dev/raw/raw4 %N"
ACTION=="add",ENV{MAJOR}=="8",ENV{MINOR}=="65",RUN+="/bin/raw /dev/raw/raw4 %M %m"
KERNEL=="raw[1-4]",OWNER="grid",GROUP="asmadmin",MODE="660"

rac1:/home/grid$ kfed read /dev/raw/raw1
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:                  1914149503 ; 0x00c: 0x72179a7f
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:         ORCLDISK ; 0x000: length=8
kfdhdb.driver.reserved[0]:            0 ; 0x008: 0x00000000
kfdhdb.driver.reserved[1]:            0 ; 0x00c: 0x00000000
kfdhdb.driver.reserved[2]:            0 ; 0x010: 0x00000000
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:                CRS_0000 ; 0x028: length=8
kfdhdb.grpname:                     CRS ; 0x048: length=3
kfdhdb.fgname:                 CRS_0000 ; 0x068: length=8
kfdhdb.capname:                         ; 0x088: length=0
kfdhdb.crestmp.hi:             33091668 ; 0x0a8: HOUR=0x14 DAYS=0x2 MNTH=0xc YEAR=0x7e3
kfdhdb.crestmp.lo:           3665632256 ; 0x0ac: USEC=0x0 MSEC=0x347 SECS=0x27 MINS=0x36
kfdhdb.mntstmp.hi:             33091668 ; 0x0b0: HOUR=0x14 DAYS=0x2 MNTH=0xc YEAR=0x7e3
kfdhdb.mntstmp.lo:           3884250112 ; 0x0b4: USEC=0x0 MSEC=0x13d SECS=0x38 MINS=0x39
kfdhdb.secsize:                     512 ; 0x0b8: 0x0200
kfdhdb.blksize:                    4096 ; 0x0ba: 0x1000
kfdhdb.ausize:                  1048576 ; 0x0bc: 0x00100000
kfdhdb.mfact:                    113792 ; 0x0c0: 0x0001bc80
kfdhdb.dsksize:                    1019 ; 0x0c4: 0x000003fb
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:             33091668 ; 0x0e4: HOUR=0x14 DAYS=0x2 MNTH=0xc YEAR=0x7e3
kfdhdb.grpstmp.lo:           3665294336 ; 0x0e8: USEC=0x0 MSEC=0x1fd SECS=0x27 MINS=0x36
kfdhdb.vfstart:                     256 ; 0x0ec: 0x00000100
kfdhdb.vfend:                       288 ; 0x0f0: 0x00000120
kfdhdb.spfile:                       59 ; 0x0f4: 0x0000003b
kfdhdb.spfflg:                        1 ; 0x0f8: 0x00000001
kfdhdb.ub4spare[0]:                   0 ; 0x0fc: 0x00000000
kfdhdb.ub4spare[1]:                   0 ; 0x100: 0x00000000
kfdhdb.ub4spare[2]:                   0 ; 0x104: 0x00000000
kfdhdb.ub4spare[3]:                   0 ; 0x108: 0x00000000
kfdhdb.ub4spare[4]:                   0 ; 0x10c: 0x00000000
kfdhdb.ub4spare[5]:                   0 ; 0x110: 0x00000000
kfdhdb.ub4spare[6]:                   0 ; 0x114: 0x00000000
kfdhdb.ub4spare[7]:                   0 ; 0x118: 0x00000000
kfdhdb.ub4spare[8]:                   0 ; 0x11c: 0x00000000
kfdhdb.ub4spare[9]:                   0 ; 0x120: 0x00000000
kfdhdb.ub4spare[10]:                  0 ; 0x124: 0x00000000
kfdhdb.ub4spare[11]:                  0 ; 0x128: 0x00000000
kfdhdb.ub4spare[12]:                  0 ; 0x12c: 0x00000000
kfdhdb.ub4spare[13]:                  0 ; 0x130: 0x00000000
kfdhdb.ub4spare[14]:                  0 ; 0x134: 0x00000000
kfdhdb.ub4spare[15]:                  0 ; 0x138: 0x00000000
kfdhdb.ub4spare[16]:                  0 ; 0x13c: 0x00000000
kfdhdb.ub4spare[17]:                  0 ; 0x140: 0x00000000
kfdhdb.ub4spare[18]:                  0 ; 0x144: 0x00000000
kfdhdb.ub4spare[19]:                  0 ; 0x148: 0x00000000
kfdhdb.ub4spare[20]:                  0 ; 0x14c: 0x00000000
kfdhdb.ub4spare[21]:                  0 ; 0x150: 0x00000000
kfdhdb.ub4spare[22]:                  0 ; 0x154: 0x00000000
kfdhdb.ub4spare[23]:                  0 ; 0x158: 0x00000000
kfdhdb.ub4spare[24]:                  0 ; 0x15c: 0x00000000
kfdhdb.ub4spare[25]:                  0 ; 0x160: 0x00000000
kfdhdb.ub4spare[26]:                  0 ; 0x164: 0x00000000
kfdhdb.ub4spare[27]:                  0 ; 0x168: 0x00000000
kfdhdb.ub4spare[28]:                  0 ; 0x16c: 0x00000000
kfdhdb.ub4spare[29]:                  0 ; 0x170: 0x00000000
kfdhdb.ub4spare[30]:                  0 ; 0x174: 0x00000000
kfdhdb.ub4spare[31]:                  0 ; 0x178: 0x00000000
kfdhdb.ub4spare[32]:                  0 ; 0x17c: 0x00000000
kfdhdb.ub4spare[33]:                  0 ; 0x180: 0x00000000
kfdhdb.ub4spare[34]:                  0 ; 0x184: 0x00000000
kfdhdb.ub4spare[35]:                  0 ; 0x188: 0x00000000
kfdhdb.ub4spare[36]:                  0 ; 0x18c: 0x00000000
kfdhdb.ub4spare[37]:                  0 ; 0x190: 0x00000000
kfdhdb.ub4spare[38]:                  0 ; 0x194: 0x00000000
kfdhdb.ub4spare[39]:                  0 ; 0x198: 0x00000000
kfdhdb.ub4spare[40]:                  0 ; 0x19c: 0x00000000
kfdhdb.ub4spare[41]:                  0 ; 0x1a0: 0x00000000
kfdhdb.ub4spare[42]:                  0 ; 0x1a4: 0x00000000
kfdhdb.ub4spare[43]:                  0 ; 0x1a8: 0x00000000
kfdhdb.ub4spare[44]:                  0 ; 0x1ac: 0x00000000
kfdhdb.ub4spare[45]:                  0 ; 0x1b0: 0x00000000
kfdhdb.ub4spare[46]:                  0 ; 0x1b4: 0x00000000
kfdhdb.ub4spare[47]:                  0 ; 0x1b8: 0x00000000
kfdhdb.ub4spare[48]:                  0 ; 0x1bc: 0x00000000
kfdhdb.ub4spare[49]:                  0 ; 0x1c0: 0x00000000
kfdhdb.ub4spare[50]:                  0 ; 0x1c4: 0x00000000
kfdhdb.ub4spare[51]:                  0 ; 0x1c8: 0x00000000
kfdhdb.ub4spare[52]:                  0 ; 0x1cc: 0x00000000
kfdhdb.ub4spare[53]:                  0 ; 0x1d0: 0x00000000
kfdhdb.acdb.aba.seq:                  0 ; 0x1d4: 0x00000000
kfdhdb.acdb.aba.blk:                  0 ; 0x1d8: 0x00000000
kfdhdb.acdb.ents:                     0 ; 0x1dc: 0x0000
kfdhdb.acdb.ub2spare:                 0 ; 0x1de: 0x0000

这里有个疑问，udev 更改磁盘绑定策略 （ 由之前绑定盘名  改为  绑定 uuid ）, start_udev 会写磁盘头？？

这个环境中有4块共享磁盘，raw1-3是集群的CRS磁盘，raw4还没有给集群使用

1. 下面使用dd命令，分别对udev绑定设备名和绑定UUID后的raw1进行dd磁盘前4K

rac1:/home/grid$ dd if=/dev/raw/raw1 of=/tmp/raw1.txt bs=1k count=4

udev绑定设备名的raw1前4K，能看出来有CRS磁盘组信息

 udev绑定UUID的raw1前4K，能看出来磁盘头有改名，磁盘组信息消失

2. 因为 raw4 没有被RAC使用，先使用dd命令清空磁盘头，dd磁盘前4K，再执行 start_udev ，再dd磁盘前4K，进行对比

# dd if=/dev/zero of=/dev/raw/raw4 bs=1M count=30
$ dd if=/dev/raw/raw4 of=/tmp/raw4.txt bs=1k count=4

执行 start_udev 前的 raw4 的前4K，能看出来是空的

 执行 start_udev 后的 raw4 的前4K