kfed是没有在文档中标出的asm工具，在oracle 11gR1中被引入。可以被用来读写asm元数据，特别是磁盘头和asm元数据的内容。
kfed是一个单独的工具，不依赖与asm实例，所以可以对mounted、dismounted的磁盘组使用。其强大特性之一就是修复asm损坏的元数据。写模式的kfed功能很强大，但是用的不好的话破坏性也很大。
想要修改ASM磁盘头信息，要借助Oracle的工具kfed，而默认这个工具是没有编译的，进入$ORACLE_HOME/lib目录，对kfed工具信息编译：
$ make -f ins_rdbms.mk ikfed
帮助信息：
$ kfed -h as/mlib ASM Library [asmlib='lib'] aun/um AU number to examine or update [AUNUM=number] #检查或更新的AU号，默认是AU0或asm的磁盘头 aus/z Allocation Unit size in bytes [AUSZ=number] #AU的大小，默认是1MB，如果使用了是非默认AU大小，需要指定该参数 blkn/um Block number to examine or update [BLKNUM=number] #要读取的块号，默认是快0，或AU的第一个块 blks/z Metadata block size in bytes [BLKSZ=number] ch/ksum Update checksum before each write [CHKSUM=YES/NO] cn/t Count of AUs to process [CNT=number] de/v ASM device to examine or update [DEV=string] #asm磁盘或设备名称。关键字dev可以被省略，asm磁盘名不能省略 dm/pall Don't suppress repeated lines when dumping corrupt blocks [DMPALL=YES/NO] o/p KFED operation type [OP=READ/WRITE/MERGE/REPAIR/NEW/FORM/FIND/STRUCT] p/rovnm Name for provisioning purposes [PROVNM=string] s/eek AU number to seek to [SEEK=number] te/xt File name for translated block text [TEXT=string] ty/pe ASM metadata block type number [TYPE=number]
使用示例：
语法示例： # displays online help for the utility $ kfed -help # reads the disk header to stdout $ kfed op=read dev=/dev/emcpowera1 # reads the specified AU and block into file /tmp/test $ kfed op=read dev=/dev/emcpowera1 aunum=3 blknum=3 text=/tmp/test # writes from /tmp/test into the specified AU and block #block checksum is computed and written together with data $ kfed op=write dev=/dev/emcpowera1 aunum=3 blknum=3 text=/tmp/test
#下面的命令相当于 kfed op=read aun=0 aus=1048576 blkn=0 dev=/dev/crs01 $ kfed read /dev/crs01 |more kfbh.endian: 1 ; 0x000: 0x01 kfbh.hard: 130 ; 0x001: 0x82 kfbh.type: 1 ; 0x002: KFBTYP_DISKHEAD #表明是磁盘头 kfbh.datfmt: 1 ; 0x003: 0x01 kfbh.block.blk: 0 ; 0x004: blk=0 kfbh.block.obj: 2147483648 ; 0x008: disk=0 kfbh.check: 229442752 ; 0x00c: 0x0dad04c0 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部分是真正的asm磁盘头的元数据块内容 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: 33026792 ; 0x0a8: HOUR=0x8 DAYS=0x17 MNTH=0xc YEAR=0x7df kfdhdb.crestmp.lo: 3576811520 ; 0x0ac: USEC=0x0 MSEC=0x74 SECS=0x13 MINS=0x35 kfdhdb.mntstmp.hi: 33033488 ; 0x0b0: HOUR=0x10 DAYS=0x8 MNTH=0x3 YEAR=0x7e0 kfdhdb.mntstmp.lo: 2552773632 ; 0x0b4: USEC=0x0 MSEC=0x20f SECS=0x2 MINS=0x26 kfdhdb.secsize: 512 ; 0x0b8: 0x0200 kfdhdb.blksize: 4096 ; 0x0ba: 0x1000 kfdhdb.ausize: 1048576 ; 0x0bc: 0x00100000 kfdhdb.mfact: 113792 ; 0x0c0: 0x0001bc80 kfdhdb.dsksize: 10240 ; 0x0c4: 0x00002800 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: 33026792 ; 0x0e4: HOUR=0x8 DAYS=0x17 MNTH=0xc YEAR=0x7df kfdhdb.grpstmp.lo: 3576543232 ; 0x0e8: USEC=0x0 MSEC=0x36e SECS=0x12 MINS=0x35 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