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如何计算ASM磁盘头自动备份的位置

从10.2.0.5开始Oracle增加了自动备份asm disk header的功能,Oracle ACED Kamus通过truss kfed repair,找出了ASM备份磁盘头的位置:第二个AU的倒数第二个block。通过这个算法,我们可以计算出不同AU,磁盘头的位置:
 1M AU:510
 2M AU:1022
 4M AU:2046
 8M AU:4094
16M AU:8190
32M AU:16382
64M AU:32766

通过下面的脚本可获取备份磁盘头的block number
SQL> col compatibility for a11
SQL> col database_compatibility for a11
col path for a30
SQL> SQL> set pages 156 lines 156
col header_backup_location for a70
SQL> SQL> select 'kfed read '||path||' ausz='||allocation_unit_size||' blknum='||((allocation_unit_size/block_size)*2-2) header_backup_location from v$asm_disk a,v$asm_diskgroup b where a.group_number=b.group_number and a.group_number !=0;

HEADER_BACKUP_LOCATION
----------------------------------------------------------------------
kfed read /dev/oracleasm/disks/ASMDISK14 ausz=16777216 blknum=8190
kfed read /dev/oracleasm/disks/ASMDISK10 ausz=16777216 blknum=8190
kfed read /dev/oracleasm/disks/ASMDISK9 ausz=4194304 blknum=2046
kfed read /dev/oracleasm/disks/ASMDISK3 ausz=1048576 blknum=510
kfed read /dev/oracleasm/disks/ASMDISK2 ausz=1048576 blknum=510
kfed read /dev/oracleasm/disks/ASMDISK1 ausz=1048576 blknum=510

6 rows selected.
SQL> exit
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - Production

With the Real Application Clusters and Automatic Storage Management options


在AU大小为1M,4M,16M下查看,字段kfbh.type内容为KFBTYP_DISKHEAD,表示为磁盘头部

[oracle@ohs1 ~]$ kfed read /dev/oracleasm/disks/ASMDISK14 ausz=16777216 blknum=8190|grep kfbh.type
kfbh.type:                            1 ; 0x002: KFBTYP_DISKHEAD
[oracle@ohs1 ~]$ kfed read /dev/oracleasm/disks/ASMDISK14 ausz=16777216 blknum=0|grep kfbh.type
kfbh.type:                            1 ; 0x002: KFBTYP_DISKHEAD
[oracle@ohs1 ~]$ kfed read /dev/oracleasm/disks/ASMDISK14 ausz=16777216 blknum=8190|grep kfbh.type
kfbh.type:                            1 ; 0x002: KFBTYP_DISKHEAD
[oracle@ohs1 ~]$ kfed read /dev/oracleasm/disks/ASMDISK9 ausz=4194304 blknum=0 |grep kfbh.type
kfbh.type:                            1 ; 0x002: KFBTYP_DISKHEAD
[oracle@ohs1 ~]$ kfed read /dev/oracleasm/disks/ASMDISK9 ausz=4194304 blknum=2046|grep kfbh.type
kfbh.type:                            1 ; 0x002: KFBTYP_DISKHEAD
[oracle@ohs1 ~]$ kfed read /dev/oracleasm/disks/ASMDISK1 ausz=1048576 blknum=0|grep kfbh.type
kfbh.type:                            1 ; 0x002: KFBTYP_DISKHEAD
[oracle@ohs1 ~]$ kfed read /dev/oracleasm/disks/ASMDISK1 ausz=1048576 blknum=510|grep kfbh.type
kfbh.type:                            1 ; 0x002: KFBTYP_DISKHEAD
[oracle@ohs1 ~]$


获取ASM磁盘头备份位置的脚本

col compatibility for a11
col database_compatibility for a11
col path for a30
set pages 156 lines 156
col header_backup_location for a70
select 'kfed read '||path||' ausz='||allocation_unit_size||' blknum='||((allocation_unit_size/block_size)*2-2) header_backup_location from v$asm_disk a,v$asm_diskgroup b where a.group_number=b.group_number and a.group_number !=0;
     
      
col compatibility for a11
col database_compatibility for a11
col path for a30
set pages 156 lines 156
col header_backup_location for a70
select mount_status,header_status,mode_status,a.state,redundancy,b.sector_size,block_size,allocation_unit_size au_size,compatibility,database_compatibility,'kfed read '||path||' ausz='||allocation_unit_size||' blknum='||((allocation_unit_size/block_size)*2-2) header_backup_location from v$asm_disk a,v$asm_diskgroup b
where a.group_number=b.group_number
      and a.group_number !=0;
      
      
Reference

http://www.dbform.com/html/2012/1875.html



关键词:asm 

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