Allocation Table(AT)
每个ASM磁盘有一个Allocation Table来描述磁盘的内容。在disk中对于每个AU，AT都有一个条目llocation Table Entry(ATE)。如果AU被分配给一个ASM文件，它们包含了文件号与区号
查找Allocation Table
在ASM磁盘头(filed kfdhdb.altlocn)存储了Allocation Table的第一个块所存储的位置。在下面的例子中，显示了AT存储在块2.
SQL> select group_number,disk_number,state,name,path from v$asm_disk where group_number3;
GROUP_NUMBER DISK_NUMBER STATE NAME PATH
------------ ----------- ------------------------------ ------------------------------ ------------------------------
3 0 NORMAL DATADG_0001 /dev/raw/raw11
3 3 NORMAL DATADG_0000 /dev/raw/raw10
3 1 NORMAL DATADG_0003 /dev/raw/raw4
3 2 NORMAL DATADG_0002 /dev/raw/raw3
[oracle@jyrac1 ~]$ kfed read /dev/raw/raw10 | grep kfdhdb.altlocn kfdhdb.altlocn: 2 ; 0x0d0: 0x00000002
下面详细查看一下Allocation Table的第一个块
[oracle@jyrac1 ~]$ kfed read /dev/raw/raw10 blkn=2 | more kfbh.endian: 1 ; 0x000: 0x01 kfbh.hard: 130 ; 0x001: 0x82 kfbh.type: 3 ; 0x002: KFBTYP_ALLOCTBL kfbh.datfmt: 2 ; 0x003: 0x02 kfbh.block.blk: 2 ; 0x004: blk=2 kfbh.block.obj: 2147483651 ; 0x008: disk=3 kfbh.check: 2183627135 ; 0x00c: 0x8227817f kfbh.fcn.base: 1453 ; 0x010: 0x000005ad kfbh.fcn.wrap: 0 ; 0x014: 0x00000000 kfbh.spare1: 0 ; 0x018: 0x00000000 kfbh.spare2: 0 ; 0x01c: 0x00000000 kfdatb.aunum: 0 ; 0x000: 0x00000000 kfdatb.shrink: 448 ; 0x004: 0x01c0 kfdatb.ub2pad: 0 ; 0x006: 0x0000 kfdatb.auinfo[0].link.next: 8 ; 0x008: 0x0008 kfdatb.auinfo[0].link.prev: 8 ; 0x00a: 0x0008 kfdatb.auinfo[1].link.next: 12 ; 0x00c: 0x000c kfdatb.auinfo[1].link.prev: 12 ; 0x00e: 0x000c kfdatb.auinfo[2].link.next: 16 ; 0x010: 0x0010 kfdatb.auinfo[2].link.prev: 16 ; 0x012: 0x0010 kfdatb.auinfo[3].link.next: 20 ; 0x014: 0x0014 kfdatb.auinfo[3].link.prev: 20 ; 0x016: 0x0014 kfdatb.auinfo[4].link.next: 24 ; 0x018: 0x0018 kfdatb.auinfo[4].link.prev: 24 ; 0x01a: 0x0018 kfdatb.auinfo[5].link.next: 28 ; 0x01c: 0x001c kfdatb.auinfo[5].link.prev: 28 ; 0x01e: 0x001c kfdatb.auinfo[6].link.next: 32 ; 0x020: 0x0020 kfdatb.auinfo[6].link.prev: 32 ; 0x022: 0x0020 kfdatb.spare: 0 ; 0x024: 0x00000000 kfdate[0].discriminator: 1 ; 0x028: 0x00000001 kfdate[0].allo.lo: 0 ; 0x028: XNUM=0x0 kfdate[0].allo.hi: 8388608 ; 0x02c: V=1 I=0 H=0 FNUM=0x0 kfdate[1].discriminator: 1 ; 0x030: 0x00000001 kfdate[1].allo.lo: 0 ; 0x030: XNUM=0x0 kfdate[1].allo.hi: 8388608 ; 0x034: V=1 I=0 H=0 FNUM=0x0 kfdate[2].discriminator: 1 ; 0x038: 0x00000001 kfdate[2].allo.lo: 0 ; 0x038: XNUM=0x0 kfdate[2].allo.hi: 8388611 ; 0x03c: V=1 I=0 H=0 FNUM=0x3 kfdate[3].discriminator: 1 ; 0x040: 0x00000001 kfdate[3].allo.lo: 4 ; 0x040: XNUM=0x4 kfdate[3].allo.hi: 8388611 ; 0x044: V=1 I=0 H=0 FNUM=0x3 kfdate[4].discriminator: 1 ; 0x048: 0x00000001 kfdate[4].allo.lo: 8 ; 0x048: XNUM=0x8 kfdate[4].allo.hi: 8388611 ; 0x04c: V=1 I=0 H=0 FNUM=0x3
从kfdatb.aunum=0，可知AU0是AT块中的第一个AU。kfdatb.shrink=448，意味着AT块可以容纳448个AU的信息。按着这个逻辑我们应该在下一个AT块中看到kfdatb.aunum=448
[oracle@jyrac1 ~]$ kfed read /dev/raw/raw10 blkn=3 | grep kfdatb.aunum kfdatb.aunum: 448 ; 0x000: 0x000001c0
以此类推，在一下AT块中将看到kfdatb.aunum=896:
[oracle@jyrac1 ~]$ kfed read /dev/raw/raw10 blkn=4 | grep kfdatb.aunum kfdatb.aunum: 896 ; 0x000: 0x00000380
Allocation table条目
对于分配的AUs，Allocation Table条目(kfdate[i])包含extent number,file number与AU的状态–正常分配(flag V=1)，可用或未人分配AU(flag V=0)。下面的命令查看Allocation table block 4
[oracle@jyrac1 ~]$ kfed read /dev/raw/raw10 blkn=4 | more kfbh.endian: 1 ; 0x000: 0x01 kfbh.hard: 130 ; 0x001: 0x82 kfbh.type: 3 ; 0x002: KFBTYP_ALLOCTBL kfbh.datfmt: 2 ; 0x003: 0x02 kfbh.block.blk: 4 ; 0x004: blk=4 kfbh.block.obj: 2147483651 ; 0x008: disk=3 kfbh.check: 2183629333 ; 0x00c: 0x82278a15 kfbh.fcn.base: 3319 ; 0x010: 0x00000cf7 kfbh.fcn.wrap: 0 ; 0x014: 0x00000000 kfbh.spare1: 0 ; 0x018: 0x00000000 kfbh.spare2: 0 ; 0x01c: 0x00000000 kfdatb.aunum: 896 ; 0x000: 0x00000380 kfdatb.shrink: 448 ; 0x004: 0x01c0 kfdatb.ub2pad: 0 ; 0x006: 0x0000 kfdatb.auinfo[0].link.next: 8 ; 0x008: 0x0008 kfdatb.auinfo[0].link.prev: 8 ; 0x00a: 0x0008 kfdatb.auinfo[1].link.next: 12 ; 0x00c: 0x000c kfdatb.auinfo[1].link.prev: 12 ; 0x00e: 0x000c kfdatb.auinfo[2].link.next: 16 ; 0x010: 0x0010 kfdatb.auinfo[2].link.prev: 16 ; 0x012: 0x0010 kfdatb.auinfo[3].link.next: 20 ; 0x014: 0x0014 kfdatb.auinfo[3].link.prev: 20 ; 0x016: 0x0014 kfdatb.auinfo[4].link.next: 24 ; 0x018: 0x0018 kfdatb.auinfo[4].link.prev: 24 ; 0x01a: 0x0018 kfdatb.auinfo[5].link.next: 28 ; 0x01c: 0x001c kfdatb.auinfo[5].link.prev: 28 ; 0x01e: 0x001c kfdatb.auinfo[6].link.next: 32 ; 0x020: 0x0020 kfdatb.auinfo[6].link.prev: 32 ; 0x022: 0x0020 kfdatb.spare: 0 ; 0x024: 0x00000000 kfdate[0].discriminator: 1 ; 0x028: 0x00000001 kfdate[0].allo.lo: 1082 ; 0x028: XNUM=0x43a kfdate[0].allo.hi: 8388867 ; 0x02c: V=1 I=0 H=0 FNUM=0x103 kfdate[1].discriminator: 1 ; 0x030: 0x00000001 kfdate[1].allo.lo: 1085 ; 0x030: XNUM=0x43d kfdate[1].allo.hi: 8388867 ; 0x034: V=1 I=0 H=0 FNUM=0x103 ...... kfdate[284].allo.hi: 8388868 ; 0x90c: V=1 I=0 H=0 FNUM=0x104 kfdate[285].discriminator: 1 ; 0x910: 0x00000001 kfdate[285].allo.lo: 1 ; 0x910: XNUM=0x1 kfdate[285].allo.hi: 8388869 ; 0x914: V=1 I=0 H=0 FNUM=0x105 kfdate[286].discriminator: 1 ; 0x918: 0x00000001 kfdate[286].allo.lo: 2 ; 0x918: XNUM=0x2 kfdate[286].allo.hi: 8388869 ; 0x91c: V=1 I=0 H=0 FNUM=0x105 kfdate[287].discriminator: 1 ; 0x920: 0x00000001 kfdate[287].allo.lo: 10 ; 0x920: XNUM=0xa kfdate[287].allo.hi: 8388869 ; 0x924: V=1 I=0 H=0 FNUM=0x105 kfdate[288].discriminator: 1 ; 0x928: 0x00000001 kfdate[288].allo.lo: 13 ; 0x928: XNUM=0xd kfdate[288].allo.hi: 8388869 ; 0x92c: V=1 I=0 H=0 FNUM=0x105 kfdate[289].discriminator: 1 ; 0x930: 0x00000001 kfdate[289].allo.lo: 15 ; 0x930: XNUM=0xf kfdate[289].allo.hi: 8388869 ; 0x934: V=1 I=0 H=0 FNUM=0x105 kfdate[290].discriminator: 1 ; 0x938: 0x00000001 kfdate[290].allo.lo: 18 ; 0x938: XNUM=0x12 kfdate[290].allo.hi: 8388869 ; 0x93c: V=1 I=0 H=0 FNUM=0x105 kfdate[291].discriminator: 1 ; 0x940: 0x00000001 kfdate[291].allo.lo: 25 ; 0x940: XNUM=0x19 kfdate[291].allo.hi: 8388869 ; 0x944: V=1 I=0 H=0 FNUM=0x105 kfdate[292].discriminator: 1 ; 0x948: 0x00000001 kfdate[292].allo.lo: 26 ; 0x948: XNUM=0x1a kfdate[292].allo.hi: 8388869 ; 0x94c: V=1 I=0 H=0 FNUM=0x105 kfdate[293].discriminator: 1 ; 0x950: 0x00000001 kfdate[293].allo.lo: 34 ; 0x950: XNUM=0x22 kfdate[293].allo.hi: 8388869 ; 0x954: V=1 I=0 H=0 FNUM=0x105 kfdate[294].discriminator: 1 ; 0x958: 0x00000001 kfdate[294].allo.lo: 37 ; 0x958: XNUM=0x25 kfdate[294].allo.hi: 8388869 ; 0x95c: V=1 I=0 H=0 FNUM=0x105 kfdate[295].discriminator: 1 ; 0x960: 0x00000001 kfdate[295].allo.lo: 39 ; 0x960: XNUM=0x27 kfdate[295].allo.hi: 8388869 ; 0x964: V=1 I=0 H=0 FNUM=0x105 kfdate[296].discriminator: 1 ; 0x968: 0x00000001 kfdate[296].allo.lo: 42 ; 0x968: XNUM=0x2a kfdate[296].allo.hi: 8388869 ; 0x96c: V=1 I=0 H=0 FNUM=0x105 kfdate[297].discriminator: 1 ; 0x970: 0x00000001 kfdate[297].allo.lo: 49 ; 0x970: XNUM=0x31 kfdate[297].allo.hi: 8388869 ; 0x974: V=1 I=0 H=0 FNUM=0x105 kfdate[298].discriminator: 1 ; 0x978: 0x00000001 kfdate[298].allo.lo: 50 ; 0x978: XNUM=0x32 kfdate[298].allo.hi: 8388869 ; 0x97c: V=1 I=0 H=0 FNUM=0x105 kfdate[299].discriminator: 1 ; 0x980: 0x00000001 kfdate[299].allo.lo: 58 ; 0x980: XNUM=0x3a kfdate[299].allo.hi: 8388869 ; 0x984: V=1 I=0 H=0 FNUM=0x105 kfdate[300].discriminator: 1 ; 0x988: 0x00000001 kfdate[300].allo.lo: 1 ; 0x988: XNUM=0x1 kfdate[300].allo.hi: 12583173 ; 0x98c: V=1 I=1 H=0 FNUM=0x105 kfdate[301].discriminator: 1 ; 0x990: 0x00000001 kfdate[301].allo.lo: 61 ; 0x990: XNUM=0x3d kfdate[301].allo.hi: 8388869 ; 0x994: V=1 I=0 H=0 FNUM=0x105 kfdate[302].discriminator: 1 ; 0x998: 0x00000001 kfdate[302].allo.lo: 63 ; 0x998: XNUM=0x3f kfdate[302].allo.hi: 8388869 ; 0x99c: V=1 I=0 H=0 FNUM=0x105 kfdate[303].discriminator: 1 ; 0x9a0: 0x00000001 kfdate[303].allo.lo: 66 ; 0x9a0: XNUM=0x42 kfdate[303].allo.hi: 8388869 ; 0x9a4: V=1 I=0 H=0 FNUM=0x105 kfdate[304].discriminator: 1 ; 0x9a8: 0x00000001 kfdate[304].allo.lo: 73 ; 0x9a8: XNUM=0x49 kfdate[304].allo.hi: 8388869 ; 0x9ac: V=1 I=0 H=0 FNUM=0x105 kfdate[305].discriminator: 1 ; 0x9b0: 0x00000001 kfdate[305].allo.lo: 74 ; 0x9b0: XNUM=0x4a kfdate[305].allo.hi: 8388869 ; 0x9b4: V=1 I=0 H=0 FNUM=0x105 kfdate[306].discriminator: 1 ; 0x9b8: 0x00000001 kfdate[306].allo.lo: 82 ; 0x9b8: XNUM=0x52 kfdate[306].allo.hi: 8388869 ; 0x9bc: V=1 I=0 H=0 FNUM=0x105 kfdate[307].discriminator: 1 ; 0x9c0: 0x00000001 kfdate[307].allo.lo: 85 ; 0x9c0: XNUM=0x55 kfdate[307].allo.hi: 8388869 ; 0x9c4: V=1 I=0 H=0 FNUM=0x105 kfdate[308].discriminator: 1 ; 0x9c8: 0x00000001 kfdate[308].allo.lo: 87 ; 0x9c8: XNUM=0x57 kfdate[308].allo.hi: 8388869 ; 0x9cc: V=1 I=0 H=0 FNUM=0x105 kfdate[309].discriminator: 1 ; 0x9d0: 0x00000001 kfdate[309].allo.lo: 90 ; 0x9d0: XNUM=0x5a kfdate[309].allo.hi: 8388869 ; 0x9d4: V=1 I=0 H=0 FNUM=0x105 kfdate[310].discriminator: 1 ; 0x9d8: 0x00000001 kfdate[310].allo.lo: 97 ; 0x9d8: XNUM=0x61 kfdate[310].allo.hi: 8388869 ; 0x9dc: V=1 I=0 H=0 FNUM=0x105 kfdate[311].discriminator: 1 ; 0x9e0: 0x00000001 kfdate[311].allo.lo: 98 ; 0x9e0: XNUM=0x62 kfdate[311].allo.hi: 8388869 ; 0x9e4: V=1 I=0 H=0 FNUM=0x105 kfdate[312].discriminator: 1 ; 0x9e8: 0x00000001 kfdate[312].allo.lo: 106 ; 0x9e8: XNUM=0x6a kfdate[312].allo.hi: 8388869 ; 0x9ec: V=1 I=0 H=0 FNUM=0x105 kfdate[313].discriminator: 1 ; 0x9f0: 0x00000001 kfdate[313].allo.lo: 109 ; 0x9f0: XNUM=0x6d kfdate[313].allo.hi: 8388869 ; 0x9f4: V=1 I=0 H=0 FNUM=0x105 kfdate[314].discriminator: 1 ; 0x9f8: 0x00000001 kfdate[314].allo.lo: 111 ; 0x9f8: XNUM=0x6f kfdate[314].allo.hi: 8388869 ; 0x9fc: V=1 I=0 H=0 FNUM=0x105 kfdate[315].discriminator: 1 ; 0xa00: 0x00000001 kfdate[315].allo.lo: 114 ; 0xa00: XNUM=0x72 kfdate[315].allo.hi: 8388869 ; 0xa04: V=1 I=0 H=0 FNUM=0x105 kfdate[316].discriminator: 1 ; 0xa08: 0x00000001 kfdate[316].allo.lo: 121 ; 0xa08: XNUM=0x79 kfdate[316].allo.hi: 8388869 ; 0xa0c: V=1 I=0 H=0 FNUM=0x105 kfdate[317].discriminator: 1 ; 0xa10: 0x00000001 kfdate[317].allo.lo: 122 ; 0xa10: XNUM=0x7a kfdate[317].allo.hi: 8388869 ; 0xa14: V=1 I=0 H=0 FNUM=0x105 kfdate[318].discriminator: 1 ; 0xa18: 0x00000001 kfdate[318].allo.lo: 130 ; 0xa18: XNUM=0x82 kfdate[318].allo.hi: 8388869 ; 0xa1c: V=1 I=0 H=0 FNUM=0x105 kfdate[319].discriminator: 1 ; 0xa20: 0x00000001 kfdate[319].allo.lo: 133 ; 0xa20: XNUM=0x85 kfdate[319].allo.hi: 8388869 ; 0xa24: V=1 I=0 H=0 FNUM=0x105 kfdate[320].discriminator: 1 ; 0xa28: 0x00000001 kfdate[320].allo.lo: 135 ; 0xa28: XNUM=0x87 kfdate[320].allo.hi: 8388869 ; 0xa2c: V=1 I=0 H=0 FNUM=0x105 kfdate[321].discriminator: 1 ; 0xa30: 0x00000001 kfdate[321].allo.lo: 138 ; 0xa30: XNUM=0x8a kfdate[321].allo.hi: 8388869 ; 0xa34: V=1 I=0 H=0 FNUM=0x105 kfdate[322].discriminator: 1 ; 0xa38: 0x00000001 kfdate[322].allo.lo: 145 ; 0xa38: XNUM=0x91 kfdate[322].allo.hi: 8388869 ; 0xa3c: V=1 I=0 H=0 FNUM=0x105 kfdate[323].discriminator: 1 ; 0xa40: 0x00000001 kfdate[323].allo.lo: 146 ; 0xa40: XNUM=0x92 kfdate[323].allo.hi: 8388869 ; 0xa44: V=1 I=0 H=0 FNUM=0x105 kfdate[324].discriminator: 1 ; 0xa48: 0x00000001 kfdate[324].allo.lo: 154 ; 0xa48: XNUM=0x9a kfdate[324].allo.hi: 8388869 ; 0xa4c: V=1 I=0 H=0 FNUM=0x105 kfdate[325].discriminator: 1 ; 0xa50: 0x00000001 kfdate[325].allo.lo: 157 ; 0xa50: XNUM=0x9d kfdate[325].allo.hi: 8388869 ; 0xa54: V=1 I=0 H=0 FNUM=0x105 kfdate[326].discriminator: 1 ; 0xa58: 0x00000001 kfdate[326].allo.lo: 159 ; 0xa58: XNUM=0x9f kfdate[326].allo.hi: 8388869 ; 0xa5c: V=1 I=0 H=0 FNUM=0x105 kfdate[327].discriminator: 1 ; 0xa60: 0x00000001 kfdate[327].allo.lo: 162 ; 0xa60: XNUM=0xa2 kfdate[327].allo.hi: 8388869 ; 0xa64: V=1 I=0 H=0 FNUM=0x105 kfdate[328].discriminator: 1 ; 0xa68: 0x00000001 kfdate[328].allo.lo: 169 ; 0xa68: XNUM=0xa9 kfdate[328].allo.hi: 8388869 ; 0xa6c: V=1 I=0 H=0 FNUM=0x105 kfdate[329].discriminator: 1 ; 0xa70: 0x00000001 kfdate[329].allo.lo: 170 ; 0xa70: XNUM=0xaa kfdate[329].allo.hi: 8388869 ; 0xa74: V=1 I=0 H=0 FNUM=0x105 kfdate[330].discriminator: 1 ; 0xa78: 0x00000001 kfdate[330].allo.lo: 178 ; 0xa78: XNUM=0xb2 kfdate[330].allo.hi: 8388869 ; 0xa7c: V=1 I=0 H=0 FNUM=0x105 kfdate[331].discriminator: 1 ; 0xa80: 0x00000001 kfdate[331].allo.lo: 181 ; 0xa80: XNUM=0xb5 kfdate[331].allo.hi: 8388869 ; 0xa84: V=1 I=0 H=0 FNUM=0x105 kfdate[332].discriminator: 1 ; 0xa88: 0x00000001 kfdate[332].allo.lo: 183 ; 0xa88: XNUM=0xb7 kfdate[332].allo.hi: 8388869 ; 0xa8c: V=1 I=0 H=0 FNUM=0x105 kfdate[333].discriminator: 1 ; 0xa90: 0x00000001 kfdate[333].allo.lo: 186 ; 0xa90: XNUM=0xba kfdate[333].allo.hi: 8388869 ; 0xa94: V=1 I=0 H=0 FNUM=0x105 kfdate[334].discriminator: 1 ; 0xa98: 0x00000001 kfdate[334].allo.lo: 193 ; 0xa98: XNUM=0xc1 kfdate[334].allo.hi: 8388869 ; 0xa9c: V=1 I=0 H=0 FNUM=0x105 kfdate[335].discriminator: 1 ; 0xaa0: 0x00000001 kfdate[335].allo.lo: 194 ; 0xaa0: XNUM=0xc2 kfdate[335].allo.hi: 8388869 ; 0xaa4: V=1 I=0 H=0 FNUM=0x105 kfdate[336].discriminator: 1 ; 0xaa8: 0x00000001 kfdate[336].allo.lo: 202 ; 0xaa8: XNUM=0xca kfdate[336].allo.hi: 8388869 ; 0xaac: V=1 I=0 H=0 FNUM=0x105 kfdate[337].discriminator: 1 ; 0xab0: 0x00000001 kfdate[337].allo.lo: 205 ; 0xab0: XNUM=0xcd kfdate[337].allo.hi: 8388869 ; 0xab4: V=1 I=0 H=0 FNUM=0x105 kfdate[338].discriminator: 1 ; 0xab8: 0x00000001 kfdate[338].allo.lo: 207 ; 0xab8: XNUM=0xcf kfdate[338].allo.hi: 8388869 ; 0xabc: V=1 I=0 H=0 FNUM=0x105 kfdate[339].discriminator: 1 ; 0xac0: 0x00000001 kfdate[339].allo.lo: 210 ; 0xac0: XNUM=0xd2 kfdate[339].allo.hi: 8388869 ; 0xac4: V=1 I=0 H=0 FNUM=0x105 kfdate[340].discriminator: 1 ; 0xac8: 0x00000001 kfdate[340].allo.lo: 217 ; 0xac8: XNUM=0xd9 kfdate[340].allo.hi: 8388869 ; 0xacc: V=1 I=0 H=0 FNUM=0x105 kfdate[341].discriminator: 1 ; 0xad0: 0x00000001 kfdate[341].allo.lo: 218 ; 0xad0: XNUM=0xda kfdate[341].allo.hi: 8388869 ; 0xad4: V=1 I=0 H=0 FNUM=0x105 kfdate[342].discriminator: 1 ; 0xad8: 0x00000001 kfdate[342].allo.lo: 226 ; 0xad8: XNUM=0xe2 kfdate[342].allo.hi: 8388869 ; 0xadc: V=1 I=0 H=0 FNUM=0x105 kfdate[343].discriminator: 1 ; 0xae0: 0x00000001 kfdate[343].allo.lo: 229 ; 0xae0: XNUM=0xe5 kfdate[343].allo.hi: 8388869 ; 0xae4: V=1 I=0 H=0 FNUM=0x105 kfdate[344].discriminator: 1 ; 0xae8: 0x00000001 kfdate[344].allo.lo: 231 ; 0xae8: XNUM=0xe7 kfdate[344].allo.hi: 8388869 ; 0xaec: V=1 I=0 H=0 FNUM=0x105 kfdate[345].discriminator: 1 ; 0xaf0: 0x00000001 kfdate[345].allo.lo: 234 ; 0xaf0: XNUM=0xea kfdate[345].allo.hi: 8388869 ; 0xaf4: V=1 I=0 H=0 FNUM=0x105 kfdate[346].discriminator: 1 ; 0xaf8: 0x00000001 kfdate[346].allo.lo: 241 ; 0xaf8: XNUM=0xf1 kfdate[346].allo.hi: 8388869 ; 0xafc: V=1 I=0 H=0 FNUM=0x105 kfdate[347].discriminator: 1 ; 0xb00: 0x00000001 kfdate[347].allo.lo: 242 ; 0xb00: XNUM=0xf2 kfdate[347].allo.hi: 8388869 ; 0xb04: V=1 I=0 H=0 FNUM=0x105 kfdate[348].discriminator: 1 ; 0xb08: 0x00000001 kfdate[348].allo.lo: 250 ; 0xb08: XNUM=0xfa kfdate[348].allo.hi: 8388869 ; 0xb0c: V=1 I=0 H=0 FNUM=0x105 kfdate[349].discriminator: 1 ; 0xb10: 0x00000001 kfdate[349].allo.lo: 253 ; 0xb10: XNUM=0xfd kfdate[349].allo.hi: 8388869 ; 0xb14: V=1 I=0 H=0 FNUM=0x105 kfdate[350].discriminator: 1 ; 0xb18: 0x00000001 kfdate[350].allo.lo: 255 ; 0xb18: XNUM=0xff kfdate[350].allo.hi: 8388869 ; 0xb1c: V=1 I=0 H=0 FNUM=0x105 kfdate[351].discriminator: 1 ; 0xb20: 0x00000001 kfdate[351].allo.lo: 258 ; 0xb20: XNUM=0x102 kfdate[351].allo.hi: 8388869 ; 0xb24: V=1 I=0 H=0 FNUM=0x105 kfdate[352].discriminator: 1 ; 0xb28: 0x00000001 kfdate[352].allo.lo: 265 ; 0xb28: XNUM=0x109 kfdate[352].allo.hi: 8388869 ; 0xb2c: V=1 I=0 H=0 FNUM=0x105 kfdate[353].discriminator: 1 ; 0xb30: 0x00000001 kfdate[353].allo.lo: 266 ; 0xb30: XNUM=0x10a kfdate[353].allo.hi: 8388869 ; 0xb34: V=1 I=0 H=0 FNUM=0x105 kfdate[354].discriminator: 1 ; 0xb38: 0x00000001 kfdate[354].allo.lo: 274 ; 0xb38: XNUM=0x112 kfdate[354].allo.hi: 8388869 ; 0xb3c: V=1 I=0 H=0 FNUM=0x105 kfdate[355].discriminator: 1 ; 0xb40: 0x00000001 kfdate[355].allo.lo: 277 ; 0xb40: XNUM=0x115 kfdate[355].allo.hi: 8388869 ; 0xb44: V=1 I=0 H=0 FNUM=0x105 kfdate[356].discriminator: 1 ; 0xb48: 0x00000001 kfdate[356].allo.lo: 279 ; 0xb48: XNUM=0x117 kfdate[356].allo.hi: 8388869 ; 0xb4c: V=1 I=0 H=0 FNUM=0x105 kfdate[357].discriminator: 1 ; 0xb50: 0x00000001 kfdate[357].allo.lo: 282 ; 0xb50: XNUM=0x11a kfdate[357].allo.hi: 8388869 ; 0xb54: V=1 I=0 H=0 FNUM=0x105 kfdate[358].discriminator: 1 ; 0xb58: 0x00000001 kfdate[358].allo.lo: 289 ; 0xb58: XNUM=0x121 kfdate[358].allo.hi: 8388869 ; 0xb5c: V=1 I=0 H=0 FNUM=0x105 kfdate[359].discriminator: 1 ; 0xb60: 0x00000001 kfdate[359].allo.lo: 290 ; 0xb60: XNUM=0x122 kfdate[359].allo.hi: 8388869 ; 0xb64: V=1 I=0 H=0 FNUM=0x105 kfdate[360].discriminator: 1 ; 0xb68: 0x00000001 kfdate[360].allo.lo: 298 ; 0xb68: XNUM=0x12a kfdate[360].allo.hi: 8388869 ; 0xb6c: V=1 I=0 H=0 FNUM=0x105 kfdate[361].discriminator: 1 ; 0xb70: 0x00000001 kfdate[361].allo.lo: 301 ; 0xb70: XNUM=0x12d kfdate[361].allo.hi: 8388869 ; 0xb74: V=1 I=0 H=0 FNUM=0x105 kfdate[362].discriminator: 1 ; 0xb78: 0x00000001 kfdate[362].allo.lo: 4 ; 0xb78: XNUM=0x4 kfdate[362].allo.hi: 8388870 ; 0xb7c: V=1 I=0 H=0 FNUM=0x106 kfdate[363].discriminator: 0 ; 0x4d0: 0x00000000 kfdate[363].free.lo.next: 0 ; 0x4d0: 0x0000 kfdate[363].free.lo.prev: 0 ; 0x4d2: 0x0000 kfdate[363].free.hi: 0 ; 0x4d4: V=0 ASZM=0x0 ....
上面输出内容显示了file 261(FNUM=0x105)的Allocation Table条目，从kfdate[285]开始到kfdate[361]结束。那么这说明file 261总共有77个AU。AU号等于kfdate[i]+offset[kfdatb.aunum=896]。也就是说，AU号为285+896=1181,286+896=1182….361+896=1527。我们可以通过查询x$kffxp视图来进行验证。
SQL> select au_kffxp from x$kffxp where group_kffxp=3 and number_kffxp=261 and disk_kffxp=3 order by au_kffxp asc;
AU_KFFXP
----------
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
77 rows selected.
可用空间
在下面的kfed输出中，可以看到kfdate[363]与kfdate[364]两关键字free next，这就说明它们是可以使用的或没有分配的AU(标记V=0)。
[oracle@jyrac1 ~]$ kfed read /dev/raw/raw10 blkn=4 | more kfbh.endian: 1 ; 0x000: 0x01 kfbh.hard: 130 ; 0x001: 0x82 kfbh.type: 3 ; 0x002: KFBTYP_ALLOCTBL kfbh.datfmt: 2 ; 0x003: 0x02 kfbh.block.blk: 4 ; 0x004: blk=4 kfbh.block.obj: 2147483651 ; 0x008: disk=3 kfbh.check: 2183629333 ; 0x00c: 0x82278a15 kfbh.fcn.base: 3319 ; 0x010: 0x00000cf7 kfbh.fcn.wrap: 0 ; 0x014: 0x00000000 kfbh.spare1: 0 ; 0x018: 0x00000000 kfbh.spare2: 0 ; 0x01c: 0x00000000 kfdatb.aunum: 896 ; 0x000: 0x00000380 kfdatb.shrink: 448 ; 0x004: 0x01c0 kfdatb.ub2pad: 0 ; 0x006: 0x0000 kfdatb.auinfo[0].link.next: 8 ; 0x008: 0x0008 kfdatb.auinfo[0].link.prev: 8 ; 0x00a: 0x0008 kfdatb.auinfo[1].link.next: 12 ; 0x00c: 0x000c kfdatb.auinfo[1].link.prev: 12 ; 0x00e: 0x000c kfdatb.auinfo[2].link.next: 16 ; 0x010: 0x0010 kfdatb.auinfo[2].link.prev: 16 ; 0x012: 0x0010 kfdatb.auinfo[3].link.next: 20 ; 0x014: 0x0014 kfdatb.auinfo[3].link.prev: 20 ; 0x016: 0x0014 kfdatb.auinfo[4].link.next: 24 ; 0x018: 0x0018 kfdatb.auinfo[4].link.prev: 24 ; 0x01a: 0x0018 kfdatb.auinfo[5].link.next: 28 ; 0x01c: 0x001c kfdatb.auinfo[5].link.prev: 28 ; 0x01e: 0x001c kfdatb.auinfo[6].link.next: 32 ; 0x020: 0x0020 kfdatb.auinfo[6].link.prev: 32 ; 0x022: 0x0020 kfdatb.spare: 0 ; 0x024: 0x00000000 kfdate[0].discriminator: 1 ; 0x028: 0x00000001 kfdate[0].allo.lo: 1082 ; 0x028: XNUM=0x43a kfdate[0].allo.hi: 8388867 ; 0x02c: V=1 I=0 H=0 FNUM=0x103 kfdate[1].discriminator: 1 ; 0x030: 0x00000001 kfdate[1].allo.lo: 1085 ; 0x030: XNUM=0x43d kfdate[1].allo.hi: 8388867 ; 0x034: V=1 I=0 H=0 FNUM=0x103 ...... kfdate[284].allo.hi: 8388868 ; 0x90c: V=1 I=0 H=0 FNUM=0x104 kfdate[285].discriminator: 1 ; 0x910: 0x00000001 kfdate[285].allo.lo: 1 ; 0x910: XNUM=0x1 kfdate[285].allo.hi: 8388869 ; 0x914: V=1 I=0 H=0 FNUM=0x105 ..... kfdate[361].discriminator: 1 ; 0xb70: 0x00000001 kfdate[361].allo.lo: 301 ; 0xb70: XNUM=0x12d kfdate[361].allo.hi: 8388869 ; 0xb74: V=1 I=0 H=0 FNUM=0x105 kfdate[362].discriminator: 1 ; 0xb78: 0x00000001 kfdate[362].allo.lo: 4 ; 0xb78: XNUM=0x4 kfdate[362].allo.hi: 8388870 ; 0xb7c: V=1 I=0 H=0 FNUM=0x106 kfdate[363].discriminator: 0 ; 0x4c8: 0x00000000 kfdate[363].free.lo.next: 16 ; 0x4c8: 0x0010 kfdate[363].free.lo.prev: 16 ; 0x4ca: 0x0010 kfdate[363].free.hi: 2 ; 0x4cc: V=0 ASZM=0x2 kfdate[364].discriminator: 0 ; 0x4d0: 0x00000000 kfdate[364].free.lo.next: 0 ; 0x4d0: 0x0000 kfdate[364].free.lo.prev: 0 ; 0x4d2: 0x0000 kfdate[364].free.hi: 0 ; 0x4d4: V=0 ASZM=0x0 ....
Stride
每个AT块可以容纳448AU(AT中kfdatb.shrink=448)，并有整个AT包含254个块(kfdfsb.max=254)。这意味着一个AT可以容纳254*448=113792个AU。这叫作stride，并且stride大小用AU的数量来表示，也就是ASM disk header中的kfdhdb.mfact的值(kfdhdb.mfact=113792)
[grid@jyrac1 ~]$ kfed read /dev/raw/raw10 aun=0 blkn=4 | grep kfdatb.shrink kfdatb.shrink: 448 ; 0x004: 0x01c0 [grid@jyrac1 ~]$ kfed read /dev/raw/raw10 aun=0 blkn=1 | grep kfdfsb.max kfdfsb.max: 254 ; 0x004: 0x00fe [grid@jyrac1 ~]$ kfed read /dev/raw/raw10 aun=0 blkn=0 | grep kfdhdb.mfact kfdhdb.mfact: 113792 ; 0x0c0: 0x0001bc80
上面显示的stride大小是AU大小为1MB的例子，因为1MB的AU在AU0中可以容纳256个block,因为blcok 0属于disk header，燕且block 1属于Free Space Table，所以只有254个block给AT block使用。
当AU大小为4MB(在exadata中是缺省值)，stride的大小将为454272个AU或1817088MB。当使用较大AU大小时，stride也会增长。下面是linux环境下，AU大小为16M时的stride大小也为454272
[grid@jyrac1 ~]$ kfed read /dev/raw/raw5 aun=0 blkn=0 | grep kfdhdb.mfact kfdhdb.mfact: 454272 ; 0x0c0: 0x0006ee80 [grid@jyrac1 ~]$ kfed read /dev/raw/raw5 aun=0 blkn=0 | grep kfdhdb.ausize kfdhdb.ausize: 16777216 ; 0x0bc: 0x01000000
多个Allocation Tables
对于较大的ASM磁盘可能有多个stride。每个stride包含属于它自己的物理地址元数据，这意味着它将有属于它自己的AT。
第二个stride在stride中的第一个AU中存储了它的物理地址元数据，执行以下命令来进行验证
[grid@jyrac1 ~]$ kfed read /dev/raw/raw10 | grep mfact kfdhdb.mfact: 113792 ; 0x0c0: 0x0001bc80
上面的输出显示stride的大小为113792个AU。我们来检查第二个stride中的AT条目。这些条目应该存储在AU 113792中的block 2-255中。
[grid@db1 ~]$ kfed read /dev/oracleasm/disks/RLZY_DATA1 | grep mfact kfdhdb.mfact: 113792 ; 0x0c0: 0x0001bc80 [grid@db1 ~]$ kfed read /dev/oracleasm/disks/RLZY_DATA1 aun=113792 blkn=2 | grep type kfbh.type: 3 ; 0x002: KFBTYP_ALLOCTBL [grid@db1 ~]$ kfed read /dev/oracleasm/disks/RLZY_DATA1 aun=113792 blkn=20 | grep type kfbh.type: 3 ; 0x002: KFBTYP_ALLOCTBL [grid@db1 ~]$ kfed read /dev/oracleasm/disks/RLZY_DATA1 aun=113792 blkn=200 | grep type kfbh.type: 3 ; 0x002: KFBTYP_ALLOCTBL [grid@db1 ~]$ kfed read /dev/oracleasm/disks/RLZY_DATA1 aun=113792 blkn=255 | grep type kfbh.type: 3 ; 0x002: KFBTYP_ALLOCTBL
上面的输出与我们所期待的一样，在AU 113792中有其它的AT存在。如果还有另一个stride，在这个stride的开始位置有另一个AT。对于一个较大的磁盘，将有多个stride，因此我们可以看到第3,4,5个stride的AT
[grid@db1 ~]$ kfed read /dev/oracleasm/disks/RLZY_DATA1 aun=227584 blkn=255 | grep type kfbh.type: 3 ; 0x002: KFBTYP_ALLOCTBL [grid@db1 ~]$ kfed read /dev/oracleasm/disks/RLZY_DATA1 aun=341376 blkn=255 | grep type kfbh.type: 3 ; 0x002: KFBTYP_ALLOCTBL [grid@db1 ~]$ kfed read /dev/oracleasm/disks/RLZY_DATA1 aun=455168 blkn=255 | grep type kfbh.type: 3 ; 0x002: KFBTYP_ALLOCTBL
小结:每个ASM磁盘至少包含一个Allocation Table(分配表)来描述磁盘的内容。AT对于磁盘中的每个allocation unit(AU)都有一个条目。如果磁盘有多个stride，每个stride有属于它自己的Allocation Table。