ASM的disk-header的备份与恢复

RAC中通常都会用到ASM，而ASM由于其高度的封装性，使得我们很难知道窥探其内部的原理。ASM如果一旦出现问题，通常都很难处理。即便在有很完备的RMAN备份的情况下，恢复起来都可能需要很长的时间。个人感觉ASM中最为脆弱的就是其diskheader。如果diskheader逻辑损坏了，即corrupt了，整个diskgroup将不能够mount，依赖于ASM实例的database也将不能够startup。RAC中增删节点后asm的diskheader就很容易出现问题。如果是因为diskheader的原因而需要重建整个diskgroup，进而用RMAN恢复是很可惜的！所以，asm的diskheader的备份至关重要！下面，简要阐述一下asm的diskheader的备份与恢复过程：ASM实例现在是能正常启动和关闭的[oracle@cuihua~]$exportORACLE_SID=+ASM[oracle@cuihua~]$sqlplus/assysdba;SQL*Plus:Release10.2.0.1.0-ProductiononSunMar922:09:572008Copyright(c)1982,2005,Oracle.Allrightsreserved.Connectedtoanidleinstance.SQLstartupASMinstancestartedTotalSystemGlobalArea83886080bytesFixedSize1217836bytesVariableSize57502420bytesASMCache25165824bytesASMdiskgroupsmountedSQLshutdownimmediateASMdiskgroupsdismountedASMinstanceshutdown通过kfed来看一下正常状态下各个asmdisk的状况[oracle@cuihuaasmdiskheader]$kfed-has/mlibASMLibrary[asmlib='lib']aun/umAUnumbertoexamineorupdate[AUNUM=number]aus/zAllocationUnitsizeinbytes[AUSZ=number]blkn/umBlocknumbertoexamineorupdate[BLKNUM=number]blks/zMetadatablocksizeinbytes[BLKSZ=number]ch/ksumUpdatechecksumbeforeeachwrite[CHKSUM=YES/NO]1cn/tCountofAUstoprocess[CNT=number]d/evASMdevicetoexamineorupdate[DEV=string]o/pKFEDoperationtype[OP=READ/WRITE/MERGE/NEW/FORM/FIND/STRUCT]p/rovnmNameforprovisioningpurposes[PROVNM=string]te/xtFilenamefortranslatedblocktext[TEXT=string]ty/peASMmetadatablocktypenumber[TYPE=number][oracle@cuihuaasmdiskheader]$kfedread/dev/raw/raw1kfbh.endian:1;0x000:0x01kfbh.hard:130;0x001:0x82kfbh.type:1;0x002:KFBTYP_DISKHEADkfbh.datfmt:1;0x003:0x01kfbh.block.blk:0;0x004:T=0NUMB=0x0kfbh.block.obj:2147483648;0x008:TYPE=0x8NUMB=0x0kfbh.check:3247695181;0x00c:0xc193e54dkfbh.fcn.base:2792;0x010:0x00000ae8kfbh.fcn.wrap:0;0x014:0x00000000kfbh.spare1:0;0x018:0x00000000kfbh.spare2:0;0x01c:0x00000000kfdhdb.driver.provstr:ORCLDISK;0x000:length=8kfdhdb.driver.reserved[0]:0;0x008:0x00000000kfdhdb.driver.reserved[1]:0;0x00c:0x00000000kfdhdb.driver.reserved[2]:0;0x010:0x00000000kfdhdb.driver.reserved[3]:0;0x014:0x00000000kfdhdb.driver.reserved[4]:0;0x018:0x00000000kfdhdb.driver.reserved[5]:0;0x01c:0x00000000kfdhdb.compat:168820736;0x020:0x0a100000kfdhdb.dsknum:0;0x024:0x0000kfdhdb.grptyp:1;0x026:KFDGTP_EXTERNALkfdhdb.hdrsts:3;0x027:KFDHDR_MEMBERkfdhdb.dskname:DATA_0000;0x028:length=9kfdhdb.grpname:DATA;0x048:length=4kfdhdb.fgname:DATA_0000;0x068:length=9kfdhdb.capname:;0x088:length=0kfdhdb.crestmp.hi:32902176;0x0a8:HOUR=0x0DAYS=0x1MNTH=0x3YEAR=0x7d8kfdhdb.crestmp.lo:52126720;0x0ac:USEC=0x0MSEC=0x2d9SECS=0x31MINS=0x0kfdhdb.mntstmp.hi:32902454;0x0b0:HOUR=0x16DAYS=0x9MNTH=0x3YEAR=0x7d8kfdhdb.mntstmp.lo:722059264;0x0b4:USEC=0x0MSEC=0x270SECS=0x30MINS=0xakfdhdb.secsize:512;0x0b8:0x02002kfdhdb.blksize:4096;0x0ba:0x1000kfdhdb.ausize:1048576;0x0bc:0x00100000kfdhdb.mfact:113792;0x0c0:0x0001bc80kfdhdb.dsksize:2048;0x0c4:0x00000800kfdhdb.pmcnt:2;0x0c8:0x00000002kfdhdb.fstlocn:1;0x0cc:0x00000001kfdhdb.altlocn:2;0x0d0:0x00000002kfdhdb.f1b1locn:2;0x0d4:0x00000002kfdhdb.redomirrors[0]:0;0x0d8:0x0000kfdhdb.redomirrors[1]:65535;0x0da:0xffffkfdhdb.redomirrors[2]:65535;0x0dc:0xffffkfdhdb.redomirrors[3]:65535;0x0de:0xffffkfdhdb.dbcompat:168820736;0x0e0:0x0a100000kfdhdb.grpstmp.hi:32902176;0x0e4:HOUR=0x0DAYS=0x1MNTH=0x3YEAR=0x7d8kfdhdb.grpstmp.lo:52090880;0x0e8:USEC=0x0MSEC=0x2b6SECS=0x31MINS=0x0kfdhdb.ub4spare[0]:0;0x0ec:0x00000000kfdhdb.ub4spare[1]:0;0x0f0:0x00000000kfdhdb.ub4spare[2]:0;0x0f4:0x00000000kfdhdb.ub4spare[3]:0;0x0f8:0x00000000kfdhdb.ub4spare[4]:0;0x0fc:0x00000000kfdhdb.ub4spare[5]:0;0x100:0x00000000kfdhdb.ub4spare[6]:0;0x104:0x00000000kfdhdb.ub4spare[7]:0;0x108:0x00000000kfdhdb.ub4spare[8]:0;0x10c:0x00000000kfdhdb.ub4spare[9]:0;0x110:0x00000000kfdhdb.ub4spare[10]:0;0x114:0x00000000kfdhdb.ub4spare[11]:0;0x118:0x00000000kfdhdb.ub4spare[12]:0;0x11c:0x00000000kfdhdb.ub4spare[13]:0;0x120:0x00000000kfdhdb.ub4spare[14]:0;0x124:0x00000000kfdhdb.ub4spare[15]:0;0x128:0x00000000kfdhdb.ub4spare[16]:0;0x12c:0x00000000kfdhdb.ub4spare[17]:0;0x130:0x00000000kfdhdb.ub4spare[18]:0;0x134:0x00000000kfdhdb.ub4spare[19]:0;0x138:0x00000000kfdhdb.ub4spare[20]:0;0x13c:0x00000000kfdhdb.ub4spare[21]:0;0x140:0x00000000kfdhdb.ub4spare[22]:0;0x144:0x00000000kfdhdb.ub4spare[23]:0;0x148:0x00000000kfdhdb.ub4spare[24]:0;0x14c:0x00000000kfdhdb.ub4spare[25]:0;0x150:0x00000000kfdhdb.ub4spare[26]:0;0x154:0x000000003kfdhdb.ub4spare[27]:0;0x158:0x00000000kfdhdb.ub4spare[28]:0;0x15c:0x00000000kfdhdb.ub4spare[29]:0;0x160:0x00000000kfdhdb.ub4spare[30]:0;0x164:0x00000000kfdhdb.ub4spare[31]:0;0x168:0x00000000kfdhdb.ub4spare[32]:0;0x16c:0x00000000kfdhdb.ub4spare[33]:0;0x170:0x00000000kfdhdb.ub4spare[34]:0;0x174:0x00000000kfdhdb.ub4spare[35]:0;0x178:0x00000000kfdhdb.ub4spare[36]:0;0x17c:0x00000000kfdhdb.ub4spare[37]:0;0x180:0x00000000kfdhdb.ub4spare[38]:0;0x184:0x00000000kfdhdb.ub4spare[39]:0;0x188:0x00000000kfdhdb.ub4spare[40]:0;0x18c:0x00000000kfdhdb.ub4spare[41]:0;0x190:0x00000000kfdhdb.ub4spare[42]:0;0x194:0x00000000kfdhdb.ub4spare[43]:0;0x198:0x00000000kfdhdb.ub4spare[44]:0;0x19c:0x00000000kfdhdb.ub4spa