Partnership and Status Table(PST)包含了关于磁盘组中所有ASM磁盘的信息，比如，磁盘号，磁盘状态，伙伴磁盘号，心跳信息与故障磁盘组信息(11g及以后版本)。PST跟踪磁盘组的成员关系与磁盘的伙伴关系。ASM为了在mount磁盘组时来判断是否有足够的一组磁盘被online就会咨询PST。每个ASM磁盘中的AU 1被保留给PST使用，但只有某些磁盘有PST数据。

PST count

在任何时候，磁盘组有受限数量的活动PSTs。PSTs的数量是由磁盘组的冗余类型与故障磁盘组数量所决定的。对于外部冗余磁盘组它只有一个PST副本。对于正常冗余磁盘组至少有两个PST副本。如果存在三个或多个故障磁盘组，它将有三个PST副本。对于高冗余磁盘组至少有三个PST副本。如果存在四个故障磁盘组，它将有四个PST副本，并且如果有五个或多个故障磁盘组，它将有五个PST副本。

下面通过例子来说明每种冗余磁盘组所包含的PST数量

1.外部冗余磁盘组

SQL> create diskgroup testdg external redundancy disk '/dev/raw/raw5','/dev/raw/raw6','/dev/raw/raw7','/dev/raw/raw12','/dev/raw/raw13','/dev/raw/raw14';Diskgroup created.

ASM alert log信息如下:

SQL> create diskgroup testdg external redundancy disk '/dev/raw/raw5','/dev/raw/raw6','/dev/raw/raw7','/dev/raw/raw12','/dev/raw/raw13','/dev/raw/raw14' NOTE: Assigning number (4,0) to disk (/dev/raw/raw5)NOTE: Assigning number (4,1) to disk (/dev/raw/raw6)NOTE: Assigning number (4,2) to disk (/dev/raw/raw7)NOTE: Assigning number (4,3) to disk (/dev/raw/raw12)NOTE: Assigning number (4,4) to disk (/dev/raw/raw13)NOTE: Assigning number (4,5) to disk (/dev/raw/raw14)NOTE: initializing header on grp 4 disk TESTDG_0000NOTE: initializing header on grp 4 disk TESTDG_0001NOTE: initializing header on grp 4 disk TESTDG_0002NOTE: initializing header on grp 4 disk TESTDG_0003NOTE: initializing header on grp 4 disk TESTDG_0004NOTE: initializing header on grp 4 disk TESTDG_0005NOTE: initiating PST update: grp = 4Thu Dec 22 08:51:03 2016GMON updating group 4 at 16 for pid 30, osid 6861NOTE: group TESTDG: initial PST location: disk 0000 (PST copy 0)NOTE: PST update grp = 4 completed successfully

从上面的信息可以看到只有一个PST副本

2.正常冗余磁盘组

SQL> create diskgroup testdg normal redundancy disk '/dev/raw/raw5','/dev/raw/raw6','/dev/raw/raw7','/dev/raw/raw12','/dev/raw/raw13','/dev/raw/raw14';Diskgroup created.

ASM alert log信息如下:

SQL> create diskgroup testdg normal redundancy disk '/dev/raw/raw5','/dev/raw/raw6','/dev/raw/raw7','/dev/raw/raw12','/dev/raw/raw13','/dev/raw/raw14' NOTE: Assigning number (4,0) to disk (/dev/raw/raw5)NOTE: Assigning number (4,1) to disk (/dev/raw/raw6)NOTE: Assigning number (4,2) to disk (/dev/raw/raw7)NOTE: Assigning number (4,3) to disk (/dev/raw/raw12)NOTE: Assigning number (4,4) to disk (/dev/raw/raw13)NOTE: Assigning number (4,5) to disk (/dev/raw/raw14)NOTE: initializing header on grp 4 disk TESTDG_0000NOTE: initializing header on grp 4 disk TESTDG_0001NOTE: initializing header on grp 4 disk TESTDG_0002NOTE: initializing header on grp 4 disk TESTDG_0003NOTE: initializing header on grp 4 disk TESTDG_0004NOTE: initializing header on grp 4 disk TESTDG_0005Fri Dec 23 08:05:45 2016GMON updating for reconfiguration, group 4 at 24 for pid 30, osid 6861NOTE: group 4 PST updated.NOTE: initiating PST update: grp = 4GMON updating group 4 at 25 for pid 30, osid 6861NOTE: group TESTDG: initial PST location: disk 0000 (PST copy 0)NOTE: group TESTDG: initial PST location: disk 0001 (PST copy 1)NOTE: group TESTDG: initial PST location: disk 0002 (PST copy 2)NOTE: PST update grp = 4 completed successfully

从上面的信息可以看到有三个PST副本

3.高冗余磁盘组

SQL> create diskgroup testdg high redundancy disk '/dev/raw/raw5','/dev/raw/raw6','/dev/raw/raw7','/dev/raw/raw12','/dev/raw/raw13','/dev/raw/raw14';Diskgroup created.

ASM alert log信息如下:

SQL> create diskgroup testdg high redundancy disk '/dev/raw/raw5','/dev/raw/raw6','/dev/raw/raw7','/dev/raw/raw12','/dev/raw/raw13','/dev/raw/raw14' NOTE: Assigning number (4,0) to disk (/dev/raw/raw5)NOTE: Assigning number (4,1) to disk (/dev/raw/raw6)NOTE: Assigning number (4,2) to disk (/dev/raw/raw7)NOTE: Assigning number (4,3) to disk (/dev/raw/raw12)NOTE: Assigning number (4,4) to disk (/dev/raw/raw13)NOTE: Assigning number (4,5) to disk (/dev/raw/raw14)NOTE: initializing header on grp 4 disk TESTDG_0000NOTE: initializing header on grp 4 disk TESTDG_0001NOTE: initializing header on grp 4 disk TESTDG_0002NOTE: initializing header on grp 4 disk TESTDG_0003NOTE: initializing header on grp 4 disk TESTDG_0004NOTE: initializing header on grp 4 disk TESTDG_0005Fri Dec 23 08:18:04 2016GMON updating for reconfiguration, group 4 at 33 for pid 30, osid 6861NOTE: group 4 PST updated.NOTE: initiating PST update: grp = 4GMON updating group 4 at 34 for pid 30, osid 6861NOTE: group TESTDG: initial PST location: disk 0000 (PST copy 0)NOTE: group TESTDG: initial PST location: disk 0001 (PST copy 1)NOTE: group TESTDG: initial PST location: disk 0002 (PST copy 2)NOTE: group TESTDG: initial PST location: disk 0003 (PST copy 3)NOTE: group TESTDG: initial PST location: disk 0004 (PST copy 4)NOTE: PST update grp = 4 completed successfully

从上面的信息可以看到有五个PST副本

PST重新定位

在以下情况下PST将会重新定位: .(在ASM启动时)磁盘的PST不可用 .磁盘脱机 .当对PST执行读/写时出现I/O错误 .磁盘被删除

对于以上情况PST将会被重新定位到相同故障磁盘组的另一个磁盘上(相同故障磁盘组中可用的磁盘上）或另一个故障磁盘组中的磁盘上(哪些不包括PST副本的磁盘）。

例如:

SQL> drop diskgroup testdg;Diskgroup dropped.SQL> create diskgroup testdg normal redundancy disk '/dev/raw/raw5','/dev/raw/raw6','/dev/raw/raw7','/dev/raw/raw12','/dev/raw/raw13','/dev/raw/raw14';Diskgroup created.

ASM alert log信息显示PST副本分布存储在disk 0,1和2:

NOTE: group TESTDG: initial PST location: disk 0000 (PST copy 0)NOTE: group TESTDG: initial PST location: disk 0001 (PST copy 1)NOTE: group TESTDG: initial PST location: disk 0002 (PST copy 2)我们现在来删除disk 0:

SQL> select disk_number, name, path from v$asm_disk_stat where group_number = (select group_number from v$asm_diskgroup_stat where name='TESTDG') order by disk_number asc;DISK_NUMBER NAME                           PATH----------- ------------------------------ ------------------------------          0 TESTDG_0000                    /dev/raw/raw5          1 TESTDG_0001                    /dev/raw/raw6          2 TESTDG_0002                    /dev/raw/raw7          3 TESTDG_0003                    /dev/raw/raw12          4 TESTDG_0004                    /dev/raw/raw13          5 TESTDG_0005                    /dev/raw/raw146 rows selected.SQL> alter diskgroup testdg drop disk TESTDG_0000;Diskgroup altered.

ASM alert log信息

SQL> alter diskgroup testdg drop disk TESTDG_0000 NOTE: GroupBlock outside rolling migration privileged regionNOTE: requesting all-instance membership refresh for group=4Fri Dec 23 09:05:37 2016GMON updating for reconfiguration, group 4 at 50 for pid 30, osid 6861NOTE: group 4 PST updated.Fri Dec 23 09:05:38 2016NOTE: membership refresh pending for group 4/0xce186197 (TESTDG)GMON querying group 4 at 51 for pid 18, osid 5012SUCCESS: refreshed membership for 4/0xce186197 (TESTDG)NOTE: starting rebalance of group 4/0xce186197 (TESTDG) at power 1SUCCESS: alter diskgroup testdg drop disk TESTDG_0000Starting background process ARB0Fri Dec 23 09:05:41 2016ARB0 started with pid=36, OS id=23811 NOTE: assigning ARB0 to group 4/0xce186197 (TESTDG) with 1 parallel I/Ocellip.ora not found.NOTE: F1X0 copy 1 relocating from 0:2 to 4:28 for diskgroup 4 (TESTDG)Fri Dec 23 09:05:53 2016NOTE: stopping process ARB0SUCCESS: rebalance completed for group 4/0xce186197 (TESTDG)NOTE: Attempting voting file refresh on diskgroup TESTDGNOTE: Refresh completed on diskgroup TESTDG. No voting file found.Fri Dec 23 09:05:53 2016NOTE: GroupBlock outside rolling migration privileged regionNOTE: requesting all-instance membership refresh for group=4Fri Dec 23 09:05:56 2016GMON updating for reconfiguration, group 4 at 52 for pid 36, osid 23854NOTE: group 4 PST updated.SUCCESS: grp 4 disk TESTDG_0000 emptiedNOTE: erasing header on grp 4 disk TESTDG_0000NOTE: process _x000_+asm1 (23854) initiating offline of disk 0.3915944465 (TESTDG_0000) with mask 0x7e in group 4NOTE: initiating PST update: grp = 4, dsk = 0/0xe9689211, mask = 0x6a, op = clearGMON updating disk modes for group 4 at 53 for pid 36, osid 23854NOTE: group TESTDG: updated PST location: disk 0001 (PST copy 0)NOTE: group TESTDG: updated PST location: disk 0002 (PST copy 1)NOTE: group TESTDG: updated PST location: disk 0003 (PST copy 2)

我们现在来删除disk 0:

SQL> select disk_number, name, path from v$asm_disk_stat where group_number = (select group_number from v$asm_diskgroup_stat where name='TESTDG') order by disk_number asc;DISK_NUMBER NAME                           PATH----------- ------------------------------ ------------------------------          0 TESTDG_0000                    /dev/raw/raw5          1 TESTDG_0001                    /dev/raw/raw6          2 TESTDG_0002                    /dev/raw/raw7          3 TESTDG_0003                    /dev/raw/raw12          4 TESTDG_0004                    /dev/raw/raw13          5 TESTDG_0005                    /dev/raw/raw146 rows selected.

PST可用性

PST表的数据要先于其他ASM元数据之前可用。当磁盘组被请求mount时，GMON进程(在ASM实例请求mount)会读取磁盘组中的所有磁盘来找到并验证所有可用的PST副本。一旦它验证有足够的PST，就会mount磁盘组。从这个时刻开始，PST表的信息储存在ASM实例的cache里；位于GMON 进程的PGA中，由PT.n.0 enqueue排他锁进行保护。对于同一集群的其他ASM实例，在启动之后会把PST表缓存在自己的GMON PGA中，加上共享的PT.n.0 enqueue。只有拥有排他PT enqueue锁的GMON进程（10gR1中为CKPT），可以更新磁盘中的PST表信息。

PST(GMON)跟踪

每次尝试mount磁盘组时，GMON trace文件就会记录PST信息。注意我说的是尝试，不是已经mount上。换句话说，GMON不管mount动作成功与否，都会记录信息。这些信息对于Oracle Support诊断磁盘组mount失败故障可能会有价值。 下面查看GMON trace文件记录的testdg磁盘组mount的信息：

[grid@jyrac1 trace]$ ls -lrt *gmon*-rw-r----- 1 grid oinstall    276 Nov 22 18:25 +ASM1_gmon_21379.trm-rw-r----- 1 grid oinstall   9953 Nov 22 18:25 +ASM1_gmon_21379.trc-rw-r----- 1 grid oinstall    631 Nov 23 07:57 +ASM1_gmon_22366.trm-rw-r----- 1 grid oinstall  26275 Nov 23 07:57 +ASM1_gmon_22366.trc-rw-r----- 1 grid oinstall    809 Nov 24 09:01 +ASM1_gmon_4906.trm-rw-r----- 1 grid oinstall  41769 Nov 24 09:01 +ASM1_gmon_4906.trc-rw-r----- 1 grid oinstall    263 Nov 24 09:06 +ASM1_gmon_18658.trm-rw-r----- 1 grid oinstall  17305 Nov 24 09:06 +ASM1_gmon_18658.trc-rw-r----- 1 grid oinstall    256 Nov 24 09:12 +ASM1_gmon_20072.trm-rw-r----- 1 grid oinstall  17274 Nov 24 09:12 +ASM1_gmon_20072.trc-rw-r----- 1 grid oinstall    263 Nov 24 09:14 +ASM1_gmon_20707.trm-rw-r----- 1 grid oinstall  17300 Nov 24 09:14 +ASM1_gmon_20707.trc-rw-r----- 1 grid oinstall    332 Nov 24 09:26 +ASM1_gmon_22827.trm-rw-r----- 1 grid oinstall  17595 Nov 24 09:26 +ASM1_gmon_22827.trc-rw-r----- 1 grid oinstall    262 Nov 24 09:48 +ASM1_gmon_26737.trm-rw-r----- 1 grid oinstall  15829 Nov 24 09:48 +ASM1_gmon_26737.trc-rw-r----- 1 grid oinstall   2175 Dec 14 16:57 +ASM1_gmon_4909.trm-rw-r----- 1 grid oinstall 178545 Dec 14 16:57 +ASM1_gmon_4909.trc-rw-r----- 1 grid oinstall   1616 Dec 23 09:05 +ASM1_gmon_5014.trm-rw-r----- 1 grid oinstall 135047 Dec 23 09:05 +ASM1_gmon_5014.trc

[grid@jyrac1 trace]$ cat +ASM1_gmon_5014.trc*** 2016-12-23 09:05:56.534GMON updating disk modes for group 4 at 53 for pid 36, osid 23854  dsk = 0/0xe9689211, mask = 0x6a, op = clearPRE=============== PST ==================== grpNum:    4 state:     1 callCnt:   53 (lockvalue) valid=1 ver=1.1 ndisks=3 flags=0x0 from inst=1 (I am 1) last=4(lockvalue) dsks: 0 1 2--------------- HDR -------------------- next: 	 4 last: 	 4 pst count: 	 3 pst locations: 	 0  1  2 incarn:   	 1 dta size: 	 6 version: 	 0 ASM version: 	 168820736 = 10.1.0.0.0contenttype: 	 0partnering pattern: 	 [ ]--------------- LOC MAP ---------------- 0: dirty 0 	 cur_loc: 0 	 stable_loc: 01: dirty 0 	 cur_loc: 1 	 stable_loc: 1--------------- DTA -------------------- 0: sts v v(rw) p(rw) a(x) d(x) fg# = 0 addTs = 0 parts: 1: sts v v(rw) p(rw) a(x) d(x) fg# = 0 addTs = 0 parts: 2 (amp) 3 (amp) 4 (amp) 5 (amp) 2: sts v v(rw) p(rw) a(x) d(x) fg# = 0 addTs = 0 parts: 1 (amp) 3 (amp) 4 (amp) 5 (amp) 3: sts v v(rw) p(rw) a(x) d(x) fg# = 0 addTs = 0 parts: 1 (amp) 2 (amp) 4 (amp) 5 (amp) 4: sts v v(rw) p(rw) a(x) d(x) fg# = 0 addTs = 0 parts: 1 (amp) 2 (amp) 3 (amp) 5 (amp) 5: sts v v(rw) p(rw) a(x) d(x) fg# = 0 addTs = 0 parts: 1 (amp) 2 (amp) 3 (amp) 4 (amp)

=== PST ===标记的部分显示了磁盘组号（grpNum）,状态，例如grpNum: 4 说明磁盘组号为4，就是testdg磁盘组

SQL> select group_number,name,block_size,allocation_unit_size,state,type from v$asm_diskgroup where group_number=4;GROUP_NUMBER NAME                           BLOCK_SIZE ALLOCATION_UNIT_SIZE STATE                  TYPE------------ ------------------------------ ---------- -------------------- ---------------------- ------------           4 TESTDG                               4096              1048576 MOUNTED                NORMAL

--- HDR ---标记的部分显示了PST的副本数（pst count）和所在的磁盘号，例如这里显示了有3个PST,分别存储在disk

0000,0001,0002pst count: 	 3 pst locations: 	 0  1  2

--- DTA ---显示了PST所在磁盘的状态

0: sts v v(rw) p(rw) a(x) d(x) fg# = 0 addTs = 0 parts: 1: sts v v(rw) p(rw) a(x) d(x) fg# = 0 addTs = 0 parts: 2 (amp) 3 (amp) 4 (amp) 5 (amp) 2: sts v v(rw) p(rw) a(x) d(x) fg# = 0 addTs = 0 parts: 1 (amp) 3 (amp) 4 (amp) 5 (amp) 3: sts v v(rw) p(rw) a(x) d(x) fg# = 0 addTs = 0 parts: 1 (amp) 2 (amp) 4 (amp) 5 (amp) 4: sts v v(rw) p(rw) a(x) d(x) fg# = 0 addTs = 0 parts: 1 (amp) 2 (amp) 3 (amp) 5 (amp) 5: sts v v(rw) p(rw) a(x) d(x) fg# = 0 addTs = 0 parts: 1 (amp) 2 (amp) 3 (amp) 4 (amp)

可以看到PST副本所在磁盘从原来的disk 0000,disk 0001,disk 0002变成了现在的disk 0001,disk 0002,disk 0003了。我们也可以使用kfed来验证PST只存在于testdg磁盘组中的disk 0001,disk 0002,disk 0003的三块磁盘上

SQL> select disk_number, name, path from v$asm_disk_stat where group_number = (select group_number from v$asm_diskgroup_stat where name='TESTDG') order by disk_number asc;DISK_NUMBER NAME                           PATH----------- ------------------------------ ------------------------------          1 TESTDG_0001                    /dev/raw/raw6          2 TESTDG_0002                    /dev/raw/raw7          3 TESTDG_0003                    /dev/raw/raw12          4 TESTDG_0004                    /dev/raw/raw13          5 TESTDG_0005                    /dev/raw/raw14

testdg中的disk 0001,0002,0003对应的磁盘就是/dev/raw/raw6,7,12:

[grid@jyrac1 trace]$ kfed read /dev/raw/raw6 aun=1 blkn=0 | grep typekfbh.type:                           17 ; 0x002: KFBTYP_PST_META[grid@jyrac1 trace]$ kfed read /dev/raw/raw6 aun=1 blkn=1 | grep typekfbh.type:                           17 ; 0x002: KFBTYP_PST_META[grid@jyrac1 trace]$ kfed read /dev/raw/raw6 aun=1 blkn=2 | grep typekfbh.type:                           18 ; 0x002: KFBTYP_PST_DTA[grid@jyrac1 trace]$ kfed read /dev/raw/raw6 aun=1 blkn=3 | grep typekfbh.type:                           18 ; 0x002: KFBTYP_PST_DTA[grid@jyrac1 trace]$ kfed read /dev/raw/raw6 aun=1 blkn=4 | grep typekfbh.type:                           13 ; 0x002: KFBTYP_PST_NONE

从上面的信息可以看到在磁盘的au 1都是用来存储PST。其中块(块号从0开始)1,2用来存储的PST元数据，块3,4用来存储的PST数据，还可以看到块5没有存储任何数据，下面的磁盘/dev/raw/raw7,12的情况与/dev/raw/raw6是一样的

[grid@jyrac1 trace]$ kfed read /dev/raw/raw7 aun=1 blkn=0 | grep typekfbh.type:                           17 ; 0x002: KFBTYP_PST_META[grid@jyrac1 trace]$ kfed read /dev/raw/raw7 aun=1 blkn=1 | grep typekfbh.type:                           17 ; 0x002: KFBTYP_PST_META[grid@jyrac1 trace]$ kfed read /dev/raw/raw7 aun=1 blkn=2 | grep typekfbh.type:                           18 ; 0x002: KFBTYP_PST_DTA[grid@jyrac1 trace]$ kfed read /dev/raw/raw7 aun=1 blkn=3 | grep typekfbh.type:                           18 ; 0x002: KFBTYP_PST_DTA[grid@jyrac1 trace]$ kfed read /dev/raw/raw7 aun=1 blkn=4 | grep typekfbh.type:                           13 ; 0x002: KFBTYP_PST_NONE[grid@jyrac1 trace]$ kfed read /dev/raw/raw12 aun=1 blkn=0 | grep typekfbh.type:                           17 ; 0x002: KFBTYP_PST_META[grid@jyrac1 trace]$ kfed read /dev/raw/raw12 aun=1 blkn=1 | grep typekfbh.type:                           17 ; 0x002: KFBTYP_PST_META[grid@jyrac1 trace]$ kfed read /dev/raw/raw12 aun=1 blkn=2 | grep typekfbh.type:                           18 ; 0x002: KFBTYP_PST_DTA[grid@jyrac1 trace]$ kfed read /dev/raw/raw12 aun=1 blkn=3 | grep typekfbh.type:                           18 ; 0x002: KFBTYP_PST_DTA[grid@jyrac1 trace]$ kfed read /dev/raw/raw12 aun=1 blkn=4 | grep typekfbh.type:                           13 ; 0x002: KFBTYP_PST_NONE

从下面的信息可以看到disk 0004,0005对应的/dev/raw/raw13,14的AU 1中没有存储PST相关数据。

[grid@jyrac1 trace]$ kfed read /dev/raw/raw13 aun=1 blkn=0 | grep typekfbh.type:                           13 ; 0x002: KFBTYP_PST_NONE[grid@jyrac1 trace]$ kfed read /dev/raw/raw14 aun=1 blkn=0 | grep typekfbh.type:                           13 ; 0x002: KFBTYP_PST_NONE

查看PST元数据

[grid@jyrac1 trace]$ kfed read /dev/raw/raw6 aun=1 blkn=0 | morekfbh.endian:                          1 ; 0x000: 0x01 --0 表示big endian,1 表示little endian.kfbh.hard:                          130 ; 0x001: 0x82 --表示HARD magic numberkfbh.type:                           17 ; 0x002: KFBTYP_PST_META --表示PST元数据块kfbh.datfmt:                          1 ; 0x003: 0x01 --表示元数据块格式kfbh.block.blk:                     256 ; 0x004: blk=256 --表示块号，那为什么这里是256，因为AU的大小是1M,块大小是4K,一个AU包含256个块，而块号是从0开始，第一个AU(AU 0)的最大块号就是255,那么第二个AU(AU 1)的第一个块的块号就是256kfbh.block.obj:              2147483649 ; 0x008: disk=1 kfbh.check:                  2539674092 ; 0x00c: 0x976059ec --做校验用的，check一致性kfbh.fcn.base:                        0 ; 0x010: 0x00000000kfbh.fcn.wrap:                        0 ; 0x014: 0x00000000kfbh.spare1:                          0 ; 0x018: 0x00000000kfbh.spare2:                          0 ; 0x01c: 0x00000000kfdpHdrBv0.time.hi:            33043177 ; 0x000: HOUR=0x9 DAYS=0x17 MNTH=0xc YEAR=0x7e0 --最后一次pst元数据的更新时间，精确到小时kfdpHdrBv0.time.lo:           395175936 ; 0x004: USEC=0x0 MSEC=0x37a SECS=0x38 MINS=0x5 --最后一次pst元数据的更新时间，精确到微秒kfdpHdrBv0.last:                      7 ; 0x008: 0x00000007 --最新的disk版本号kfdpHdrBv0.next:                      7 ; 0x00c: 0x00000007 --下一个disk版本号kfdpHdrBv0.copyCnt:                   3 ; 0x010: 0x03 --表示PST元数据的备份信息，3表示磁盘组是normal冗余。1表示磁盘组是external冗余。kfdpHdrBv0.version:                   0 ; 0x011: 0x00kfdpHdrBv0.ub2spare:                  0 ; 0x012: 0x0000kfdpHdrBv0.incarn:                    4 ; 0x014: 0x00000004kfdpHdrBv0.copy[0]:                   1 ; 0x018: 0x0001kfdpHdrBv0.copy[1]:                   2 ; 0x01a: 0x0002kfdpHdrBv0.copy[2]:                   3 ; 0x01c: 0x0003kfdpHdrBv0.copy[3]:                   0 ; 0x01e: 0x0000kfdpHdrBv0.copy[4]:                   0 ; 0x020: 0x0000kfdpHdrBv0.dtaSz:                     6 ; 0x022: 0x0006 --表示pst元数据中，diskgroup所包含的disk个数ub1[0]:                               0 ; 0x024: 0x00ub1[1]:                               0 ; 0x025: 0x00ub1[2]:                               0 ; 0x026: 0x00ub1[3]:                               0 ; 0x027: 0x00ub1[4]:                               0 ; 0x028: 0x00ub1[5]:                               0 ; 0x029: 0x00ub1[6]:                               0 ; 0x02a: 0x00ub1[7]:                               0 ; 0x02b: 0x00ub1[8]:                               0 ; 0x02c: 0x00ub1[9]:                               0 ; 0x02d: 0x00ub1[10]:                              0 ; 0x02e: 0x00ub1[11]:                              0 ; 0x02f: 0x00ub1[12]:                              0 ; 0x030: 0x00ub1[13]:                              0 ; 0x031: 0x00ub1[14]:                              0 ; 0x032: 0x00ub1[15]:                              0 ; 0x033: 0x00ub1[16]:                              0 ; 0x034: 0x00ub1[17]:                              0 ; 0x035: 0x00ub1[18]:                              0 ; 0x036: 0x00

磁盘伙伴

磁盘的Partnership是在normal或者high冗余的磁盘组上，在两个磁盘之间有一个“对称”的关系。在external冗余中，不存在disk partnership。

小结

PST（Partnership and Status Table）包含一个磁盘组里所有磁盘的相关信息 -- 磁盘号，磁盘状态，partner磁盘号，心跳信息和failgroup信息（11g之后）。每个ASM磁盘的第二AU(AU 1)被保留给PST使用，但是只有部分磁盘有PST数据。由于PST是重要的ASM元数据，只要故障磁盘组个数足够，在normal冗余中将会有三副本，在high冗余中将会有五副本。

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