3、AMDU

AMDU是筆者個人覺得最像是官方工具的一個，全稱為：ASM Metadata Dump Utility。AMDU最大的作用在於可以將ASM Disk Group和DISK所有可用後設資料資訊匯出，並且整理為可讀的格式內容。

AMDU最大的一個好處，在於其工作不受到Disk Group是否mount訪問的影響。這個工具之所以被正式公佈，主要在於Oracle Support在進行遠端支援的時候，需要客戶提供上載檔案。

工具幫助引數資訊如下：

[grid@NCR-Standby-Asm ~]$ amdu help=y

a/usize AU size for corrupt disks

-ausize <bytes>: This option must be set when -baddisks is set. It

must be a power of 2. This size is required to scan a disk looking

for metadata, and it is normally read from the disk header. The

value applies to all disks that do not have a valid header. The

value from the disk header will be used if a valid header is

found.

ba/ddisks Include disks with bad headers

-baddisks <diskgroup>: Normally disks with bad disk headers, or that

look like they were never part of a disk group, will not be

scanned. This option forces them to be scanned anyway and to be

considered part of the given diskgroup. This is most useful when

a disk header has been damaged. The disk will still need to have

a valid allocation table to drive the scan unless -fullscan is

used. In any case at least one block in the first two AUs must be

valid so that the disk number can be determined. The options

-ausize and -blksize are required since these values are normally

fetched from the disk header. If the diskgroup uses external

redundancy then -external should be specified. These values will

be compared against any valid disks found in the diskgroup and

they must be the same.

bl/ksize ASM block size for corrupt disks

-blksize <bytes>: This option must be set when -baddisks is set. It

must be a power of 2. This size is required to scan a disk looking

for metadata, and it is normally read from the disk header. The

value applies to all disks that do not have a valid header. The

value from the disk header will be used if a valid header is

found.

c/ompare Compare file mirrors

-compare: This option only applies to file extraction from a normal or

high redundancy disk group. Every extent that is mirrored on more

than one discovered disk will have all sides of its mirror

compared. If they are not identical a message will be reported

on standard error and the report file. The message will indicate

which copy was extracted. A count of the blocks that are not

identical will be in the report file.

dir/ectory Directory from previous dump

-directory <string>: This option completely eliminates the discovery

phase of operation. It specifies the name of a dump directory from

a previous run of AMDU. The report file and map files are read

instead of doing a discovery and scan. The parsing of these ASCII

files is very dependent on them being exactly as written by AMDU.

AMDU is unlikely to work properly if they have been modified by

a text editor, or if some of the files are missing or truncated.

Note that the directory may be a copy FTPed from another

machine. The other machine may even be a different platform

with a different endianess.

dis/kstring Diskstring for discovery

-diskstring <string>: By default the null string is used for

discovery. The null string should discover all disks the user has

access to. Many installations specify an asm_diskstring parameter

for their ASM instance. If so that parameter value should be given

here. Multiple discovery strings can be specified by multiple

occurrences of -diskstring <string>. Beware of shell syntax

conflicts with discovery strings. Diskstrings are usually the same

syntax the shell uses for expanding path names on command lines so

they will most likely need to be enclosed in single quotes.

du/mp Diskgroups to dump

-dump <diskgroup>: This option specifies the name of a diskgroup to

have its metadata dumped. This option may be specified multiple

times to dump multiple diskgroups. If the diskgroup name is ALL

then all diskgroups encountered will be dumped. The diskgroup name

is not case sensitive, but will be converted to uppercase for all

reports. If this option is not specified then no map or image

files will be created, but -extract and -print may still work.

exc/lude Disks to exclude

-exclude <string>: Multiple exclude options may be specified. These

strings are used for discovery just like the values for diskstring.

Only shallow discovery is done on these diskstrings. Any disks

found in the exclude discovery will not be accessed. If they are

also discovered using the -diskstring strings, then the report will

include the information from shallow discovery along with a message

indicating the disk was excluded.

exte/rnal Assume external redundancy

-external: Normally AMDU determines the diskgroup redundancy from the

disk headers. However this is not possible with the -baddisks

option. It is assumed that the redundancy of the -baddisks

diskgroup is normal or high unless this option is given to specify

external redundancy.

extr/act Files to extract

-extract <diskgroup>.<file_number>: This extracts the numbered file

from the named diskgroup, case insensitive. This option may be

specified multiple times to extract multiple files. The extracted

file is placed in the dump directory under the name

<diskgroup>_<number>.f where <diskgroup> is the diskgroup name

in uppercase, and <number> is the file number. The -output option

may be used to write the file to any location. The extracted file

will appear to have the same contents it would have if accessed

through the database. If some portion of the file is unavailable

then that portion of the output file will be filled with

0xBADFDA7A, and a message will appear on stderr.

fi/ledump Dump files rather than extract

-filedump: This option causes the file objects in the command line to

have their blocks dumped to the image files rather than extracted.

This can be combined with the -novirtual option to selectively

dump only some of the metadata files. It may also be used to dump

user files (number >= 256) so that all mirrored copies can be

examined.

fo/rmer Include dropped disks

-former: Normally disks marked as former are not scanned, but this

option will scan them and include their contents in the output.

This is useful when it is necessary to look at the contents of a

disk that was dropped. Note that dropped normal disks will not have

any entries in their allocation tables and thus only the physically

addressed extents will be dumped. Force dropped disks will not have

status former in their disk headers and are not affected by this

option. However if DROP DISKGROUP is used, the disks will have the

contents as of the time of the drop, and will be in status former.

Thus this option is useful for extracting files from a dropped

diskgroup.

fu/llscan Scan entire disk

-fullscan: This option reads every AU on the disk and looks at the

contents of the AU rather than limiting the AU's read based on the

allocation table. This is useful when the allocation table is

corrupt or needs recovery. An AU will be written to the image file

if it starts with a block that contains a valid ASM block header.

The file and extent information for the map will be extracted from

the block header. Physically addressed metadata will be dumped

regardless of its contents. This option is incompatible with

extracting a file. It is an error to specify -extract with this

option. Note that this option is likely to find old garbage

metadata in unallocated AU's since there is no means of

determining what is allocated. Thus there may be many different

copies of the same block, possibly of different versions.

h/ex Always print block contents in hex

-hex: This prints the block contents in hex without attempting to print

them as ASM metadata. This is useful when the block is known to not

be ASM metadata. It avoids the ASM block header dump and ensures

the block is not accidentally interpreted as ASM metadata. This

option requires at least one -print option.

noa/cd Do not dump ACD

-noacd: This option limits the dumping of the Active Change Directory

to just the control blocks that contain the checkpoint. There is

126 MB of ACD per ASM instance (42 MB for external redundancy). It

is normally of no interest if there has been a clean shutdown or

no updates for a while. This option avoids dumping a lot of

unimportant data. The blocks will still be read and checked for

corruption. The map file will still contain entries for the ACD

extents, but the block counts will be zero.

nod/ir Do not create a dump directory

-nodir: No dump directory is created, and no files are created in it.

The directory name is not written to standard out. The report file

is written to standard out before any block printouts from any

-print options. This option conflicts with -filedump. It is an

error to specify this and extract a file to the dump directory.

noe/xtract Do not create extracted file

-noextract: This prevents files from being extracted to an output

file, but the file will be read and any errors in selecting the

correct output will be reported. This is most useful in

combination with the -compare option.

noh/eart Do not check for heartbeat

-noheart: Normally the heartbeat block will be saved at discovery time

and checked when the disk is scanned. A sleep is added between

discovery and scanning to ensure there is time for the heartbeat

to be written. If the heartbeat block changes then it is most

likely that the diskgroup containing this disk is mounted by an

active ASM instance. An error and warning is generated but

operation proceeds normally. This option suppresses this check

and avoids the sleep.

noi/mage Do not create image files

-noimage: No image files will be created n the dump directory. All

the reads specified by the read options will still be done. The

map files may be used to find blocks on the disks themselves. In

the map file, the count of blocks dumped, the image file sequence

number, and the byte offset in the image file will all always be

zero (C00000 S0000 B0000000000)

nom/ap Do not create map or image files

-nomap: No map file is created and no image file is created. The only

output is the report file. The -noimage option is assumed if this

is set since an image file without a map is useless. The options

-noscan and -noread also result in no map or image files, but

-nomap still reads the metadata to check for I/O errors and corrupt

blocks.

nop/rint Do no print block contents

-noprint: This suppresses the printout of the block contents for

blocks printed with the -print option. It is useful for getting

just the block reports without a lot of data. This option requires

at least one -print option.

norea/d Shallow discovery only

-noread: This eliminates any reading of any disks at all. Only shallow

discovery will be done. The report will end after the discovery

section. It is an error to specify this option and specify a file

to extract or blocks to print. It is an error to specify this

and -fullscan.

norep/ort Do not generate a report

-noreport: This suppresses the generation of the report file. It is

most useful in combination with -nodir and -print to get block

printouts without a lot of clutter. It is unnecessary to include

this with -directory since no report is generated then anyway.

nosc/an Deep discovery only

-noscan: This eliminates any reading of any disks after deep

discovery. This results in just doing a deep discovery using the

disksting parameter. The report will end after the discovery

section. It is an error to specify this option and specify a file

to extract. It is an error to specify this and -fullscan.

nosu/bdir Do not create a dump directory

-nosubdir: No dump directory is created, but files are still created.

The directory name is not written to standard out. The report file

and any other dump or extract files are written to the current

directory or to the directory indicated by -parentdir. This means

that if multiple AMDU dumps are requested using this option, the

report file will always correspond to the last dump requested.

nov/irtual Do not dump virtual metadata

-novirtual: This option eliminates reading of any virtual metadata.

Only the physically addressed metadata will be read. This

implicitly eliminates the ACD and extent maps so -noacd and

-noxmap will be assumed.

nox/map Do not dump extent maps

-noxmap: This option eliminates reading of the indirect extents

containing the file extent maps. This is the bulk of the metadata

in most diskgroups. Even the entries in the map file will be

eliminated.

o/utput Files to create for extract

-output <file_name>: This option specifies a different file for

writing an extracted file. The file will be overwritten if it

already exists. This option requires that exactly one file is

extracted via the -extract option.

pa/rent Parent for dump directory

-parent <path_name>: By default the dump directory is created in the

current directory, but another directory can be specified using

this option. The parent directory for the dump directory must

already exist.

pr/int Block to print

-print <block_spec>: This option prints one or more blocks to standard

out. This option may be specified multiple times to print multiple

<block_spec>s. The printout contains information about how each

block was read as well as a formatted printout. Multiple blocks

matching the same <block_spec> may be found when scanning the

disks. For example there may be multiple disks that have headers

for the same diskgroup and disk number. If the block is from a

mirrored file then multiple copies should exist on different disks.

If multiple copies of the same block have identical contents then

only one formatted printout of the contents will be generated, but

a header will be printed for each copy. A <block_spec> may include

a count of sequential blocks to print. A <block_spec> may specify

a block either by disk or file.

<block_spec> ::= <single_block> | <single_block>.C<count>

<single_block> ::= <report_disk_block> | <group_disk_block> |

<extent_file_block> | <virtual_file_block> | <xmap_file_block>

<report_disk_block> ::=

<group_name>.N<report_number>.A<au_number>.B<block_number>

<group_disk_block> ::=

<group_name>.D<disk_number>.A<au_number>.B<block_number>

<extent_file_block> ::=

<group_name>.F<file_number>.X<physical_extent>.B<block_number>

<virtual_file_block> ::=

<group_name>.F<file_number>.V<virtual_block_number>

<xmap_file_block> ::=

<group_name>.F<file_number>.M<extent_map_block_number>

r/egistry Dump registry files

-registry: The ASM registries will be read and dumped to the image

file. There will be no block consistency checks since these files

do not have ASM cache headers. To dump one specific registry

specify -filedump and include the file object for the registry

(e.g. DATA.255).

s/pfile Extract usable spfile

-spfile: This causes extract to render the resulting file in a form

that is directly usable by startup. Without this option, AMDU

will extract the file as a regular ASM file including all ASM

specific headers and such

每次執行amdu命令，就會在當前目錄上建立出一個帶有當前時間資訊的資料夾結構。

[grid@NCR-Standby-Asm ~]$ amdu

amdu_2015_06_05_10_15_47/

[grid@NCR-Standby-Asm ~]$ ls -l | grep amdu

drwxr-xr-x 2 grid oinstall 4096 Jun 5 10:15 amdu_2015_06_05_10_15_47

進入其中，可以檢視report.txt檔案，作為資訊收集結果。

[grid@NCR-Standby-Asm ~]$ cd amdu_2015_06_05_10_15_47/

[grid@NCR-Standby-Asm amdu_2015_06_05_10_15_47]$ ls -l

total 8

-rw-r--r-- 1 grid oinstall 5350 Jun 5 10:15 report.txt

[grid@NCR-Standby-Asm amdu_2015_06_05_10_15_47]$ more report.txt

-*-amdu-*-

******************************* AMDU Settings ********************************

ORACLE_HOME = /u01/app/grid/product/11.2.0/grid

System name: Linux

Node name: NCR-Standby-Asm

Release: 2.6.32-431.el6.x86_64

Version: #1 SMP Sun Nov 10 22:19:54 EST 2013

Machine: x86_64

amdu run: 05-JUN-15 10:15:47

Endianess: 1

--------------------------------- Operations ---------------------------------

------------------------------- Disk Selection -------------------------------

-diskstring ''

------------------------------ Reading Control -------------------------------

------------------------------- Output Control -------------------------------

********************************* DISCOVERY **********************************

----------------------------- DISK REPORT N0001 ------------------------------

Disk Path: ORCL:DATA1

Unique Disk ID:

Disk Label: DATA1

Physical Sector Size: 512 bytes

Disk Size: 20489 megabytes

Group Name: DATA

Disk Name: DATA1

Failure Group Name: DATA1

Disk Number: 0

Header Status: 3

Disk Creation Time: 2015/05/05 09:27:12.410000

Last Mount Time: 2015/06/01 08:45:51.489000

Compatibility Version: 0x0b200000(11020000)

Disk Sector Size: 512 bytes

Disk size in AUs: 20489 AUs

Group Redundancy: 1

Metadata Block Size: 4096 bytes

AU Size: 1048576 bytes

Stride: 113792 AUs

Group Creation Time: 2015/05/05 09:27:12.333000

File 1 Block 1 location: AU 2

OCR Present: NO

（篇幅原因，略……）

透過加入引數，可以實現轉儲特定Disk Group的內部資訊。

[grid@NCR-Standby-Asm ~]$ cd /dev/oracleasm/disks/

[grid@NCR-Standby-Asm disks]$ ls -l

total 0

brw-rw---- 1 grid asmadmin 8, 17 May 22 16:57 DATA1

brw-rw---- 1 grid asmadmin 8, 18 May 22 16:57 DATA2

brw-rw---- 1 grid asmadmin 8, 19 May 22 16:57 DATA3

brw-rw---- 1 grid asmadmin 8, 21 May 22 16:57 DATA5

brw-rw---- 1 grid asmadmin 8, 22 May 22 16:57 DATA6

[grid@NCR-Standby-Asm oracleasm]$ cd ~

[grid@NCR-Standby-Asm ~]$ amdu -diskstring '/dev/oracleasm/disks/DATA*' -dump 'DATA'

amdu_2015_06_05_10_22_11/

[grid@NCR-Standby-Asm ~]$ cd amdu_2015_06_05_10_22_11/

[grid@NCR-Standby-Asm amdu_2015_06_05_10_22_11]$ ls -l

total 60448

-rw-r--r-- 1 grid oinstall 61882368 Jun 5 10:22 DATA_0001.img

-rw-r--r-- 1 grid oinstall 5360 Jun 5 10:22 DATA.map

-rw-r--r-- 1 grid oinstall 7325 Jun 5 10:22 report.txt

新增加檔案，為Disk Group DATA的對映資訊。

[grid@NCR-Standby-Asm amdu_2015_06_05_10_22_11]$ more DATA.map

N0001 D0000 R00 A00000000 F00000000 I0 E00000000 U00 C00256 S0001 B0000000000

N0001 D0000 R00 A00000001 F00000000 I0 E00000000 U00 C00256 S0001 B0001048576

N0001 D0000 R00 A00000002 F00000001 I0 E00000000 U00 C00256 S0001 B0002097152

N0001 D0000 R00 A00000003 F00000003 I0 E00000000 U00 C00256 S0001 B0003145728

N0001 D0000 R00 A00000004 F00000003 I0 E00000003 U00 C00256 S0001 B0004194304

N0001 D0000 R00 A00000005 F00000003 I0 E00000006 U00 C00256 S0001 B0005242880

使用-extract命令，可以直接從ASM Disk Group中抽取檔案。

SQL> show parameter control

NAME TYPE VALUE

------------------------------------ ----------- ------------------------------

control_file_record_keep_time integer 7

control_files string +DATA/sicsstb/controlfile/current.260.878897845, +RECO/sicsstb/controlfile/current.256.878897845

control_management_pack_access string DIAGNOSTIC+TUNING

嘗試抽取出控制檔案。

[grid@NCR-Standby-Asm ~]$ amdu -extract DATA.260

amdu_2015_06_05_10_27_46/

AMDU-00204: Disk N0001 is in currently mounted diskgroup DATA

AMDU-00201: Disk N0001: 'ORCL:DATA1'

關閉例項和ASM。

[grid@NCR-Standby-Asm ~]$ srvctl stop database -d sicsstb

[grid@NCR-Standby-Asm ~]$ srvctl stop asm -f

[grid@NCR-Standby-Asm ~]$ amdu -extract DATA.260

amdu_2015_06_05_10_29_25/

[grid@NCR-Standby-Asm ~]$

抽取成功，進入目錄。以ASCII格式開啟control file。

[grid@NCR-Standby-Asm ~]$ cd amdu_2015_06_05_10_29_25/

[grid@NCR-Standby-Asm amdu_2015_06_05_10_29_25]$ ls -l

total 9528

-rw-r--r-- 1 grid oinstall 9748480 Jun 5 10:29 DATA_260.f

-rw-r--r-- 1 grid oinstall 7971 Jun 5 10:29 report.txt

[grid@NCR-Standby-Asm amdu_2015_06_05_10_29_25]$ strings DATA_260.f | grep +DATA

+DATA/sicsstb/onlinelog/group_3.263.878897849

+DATA/sicsstb/onlinelog/group_2.262.878897849

+DATA/sicsstb/onlinelog/group_1.261.878897847

+DATA/sicsstb/datafile/users.259.878897773

+DATA/sicsstb/datafile/undotbs1.258.878897773

+DATA/sicsstb/datafile/sysaux.257.878897773

+DATA/sicsstb/datafile/system.256.878897771

+DATA/sicsstb/tempfile/temp.264.878897855

+DATA/sicsstb/datafile/example.265.878897857

+DATA/sicsstb/onlinelog/group_3.263.878897849

+DATA/sicsstb/onlinelog/group_2.262.878897849

+DATA/sicsstb/onlinelog/group_1.261.878897847

+DATA/sicsstb/datafile/users.259.878897773

+DATA/sicsstb/datafile/undotbs1.258.878897773

+DATA/sicsstb/datafile/sysaux.257.878897773

+DATA/sicsstb/datafile/system.256.878897771

+DATA/sicsstb/tempfile/temp.264.878897855

+DATA/sicsstb/datafile/example.265.878897857

[grid@NCR-Standby-Asm amdu_2015_06_05_10_29_25]$ strings DATA_260.f | grep +RECO

+RECO/sicsstb/onlinelog/group_3.259.878897849

+RECO/sicsstb/onlinelog/group_2.258.878897849

+RECO/sicsstb/onlinelog/group_1.257.878897849

+RECO/sicsstb/onlinelog/group_3.259.878897849

+RECO/sicsstb/onlinelog/group_2.258.878897849

+RECO/sicsstb/onlinelog/group_1.257.878897849

後續的恢復過程就容易了~

4、結論

Grid、ASM對於初學者是很頭疼的，主要在於高度的自動化讓很多人覺得神秘不可接近。“知識可以消除迷信”，在這樣的情況下，我們要抱著更加虛心的態度去學習新技術和新工具，才能跟上時代，不斷前進。

ASM管理命令列三工具：KFOD、KFED和AMDU（下）

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