If you cannot recover the data by yourself, ask Parnassusdata, the professional ORACLE database recovery team for help.
Parnassusdata Software Database Recovery Team
ASM Metadata Dump Utility (AMDU)
This is a functional description of a utility to quickly
extract all the available metadata from one or more ASM
disks and/or generate formatted printouts of individual
blocks. The dump output can be shipped back to Oracle for
analysis. The utility can be used at Oracle to generate
formatted block printouts from the dump output. The utility
does not require that any disk group is even mountable. It
also has the ability to extract one or more files from an
unmounted diskgroup and write them to the OS file system.
Operations
AMDU performs three different functions. A given execution
of AMDU may perform one, two or all three of these
functions.
1.Dump metadata from ASM disks to the OS file system for
later analysis.
2.Extract the contents of an ASM file and write it to an OS
file system even if the diskgroup is not mounted.
3.Print metadata blocks based on the C structures in the
blocks, or in hex.
The input data may be the contents of the ASM disks, or it
may be derived from a directory created by a previous run
of AMDU. The options -diskstring and -exclude are used to
specify ASM disks to read. The option -directory specifies
a directory created by a previous run of AMDU. The
directory may contain a copy of the original directory
contents. These options are incompatible with each other.
Operational Phases
The basic steps of operation are listed in this section.
Command line options provide the ability to control which
phases are executed and how they operate.
1.Discover disks: This uses ASM discovery to find a set of
disks. The headers are read to determine which disks are
in which diskgroups. The disks to be scanned in the next
phase are chosen. The results of the discovery are put in
the report file. With the option -directory, reading the
existing report file rather than creating a new one
accomplishes this phase.
2.Scan disks: The allocation tables of disks are scanned.
Based on the allocation table entries and command line
options, interesting blocks are written to image files.
Map files are created describing the interesting AU's and
where they were written to the image files. If any files
are being extracted, their extent maps are constructed in
memory from the allocation table entries (extent maps are
ignored). If any blocks are being printed the location of
the blocks is saved in memory. With the -directory option
this phase is accomplished by reading the existing map
files rather than creating map and image files.
3.Extract files: The extent maps of files to extract are
sorted. The file data is read from the ASM disks and
written to output files. If -directory is specified for extraction of
an ASM metadata file, the map and image files are read to build
the extent maps.
4.Printout blocks: Formatted block printouts are written to
standard out along with information about how the block
data was read. A kfed command to dump the block on the
system where the report was generated is also printed.
With the -directory option the data is read from the
image files.
Output Files
Four types of ouptut files are created by AMDU. They are
all placed in a new dump directory. The file names are
automatically generated by AMDU. A new dump directory is
created for each run so the output files can be easily
tarred and zipped to send back to Oracle. The name of the
directory is based on the time and date to one second
resolution. The directory name is written to standard out
before any files are created in the directory. Note that
the directory name is relative to the current directory
unless a full path name is specified on the command line
with the -parent option.
If AMDU is run with the -directory option then no dump
directory and no output files are created. Instead the -
directory option specifies the location of a previously
created dump directory. In this case -print can be
specified to generate formatted block printouts from the
previously created dump directory. The printouts are sent
to standard out rather than creating a new file. If -extract
is specified with -directory, -output is required to indicate
the location of the extracted file.
Extracted Files
One extracted file is created for every file listed under
the -extract option on the command line. Normally, the extracted
file is placed in the dump directory under the name
<group>_<number>.f where <group> is the diskgroup name in
uppercase, and <number> is the file number of the file specified
on the command line. 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.
The -output option can be used to extract a single file to
a specific file name rather than the dump directory. This
can be used in combination with -nodir option to avoid the
creation of a dump directory completely. If -directory is
specified, -output is required.
Image Files
Image files contain block images from the ASM disks. This
is the raw data that is copied from the disks. Since there
can be a lot of data, and some file systems have problems
with large files, an image file is always smaller than 2
gigabytes. When there is more that 2Gb of data, multiple
image files are created. An image file may contain data
from multiple disks, but only from disks that are part of
the same disk group (according to the disk's header). All
the data from one disk will be grouped together in the
image files (possibly spanning a file boundary). Blocks
from a single allocation unit will always be adjacent and
not span image files. Uninteresting data, such as empty
blocks, will not be dumped, so a partial AU might be in the
dump. Thus the size of a full image file is not constant.
Disks that have been dropped from a disk group will still
contain the group name in their header and may be included
in the image files for that disk group if the -former
option is specified. Note that, unlike mount, the PST is
not consulted to decide which disks are parts of the disk
group. Disks which were forcibly dropped will be included
even without the -former option.
Image file names are constructed from the group name and a
sequence number. The form is as follows where <group> is
the group name in uppercase, and <NNNN> is the sequence
number including leading zeroes. The first image file has
sequence number 0001.
<group>_<NNNN>.img
Map Files
Map files are ASCII files that describe the data in the
image files for a particular disk group. AMDU creates one
map file for each series of image files, i.e. one map file
per disk group. The map file contains one line for each
allocation unit that has contents dumped to an image file.
Some allocation units may have an entry in the map file
even though nothing was written to the image file. Every
line has the same fields of the same length. The lines are
in the order of the data in the image file, but contain
absolute references to the locations in the image file so
that they can be sorted into different orders without
losing track of where the AU is stored in the image files.
The following fields appear in each line. The fields are
separated by blanks. Each field starts with a unique letter
immediately followed by a decimal number with leading
zeroes. This should facilitate using sort and grep to
reorganize the map. In the following descriptions the
leading letter and the number of decimal digits are given
within parentheses. For example (D4) means the letter 'D'
followed by 4 decimal digits.
1.Disk Report Number (N4): Every disk discovered by shallow
discovery is assigned a disk report number. This number
is printed in the report file along with information
about the disk. Two disks from the same diskgroup with
the same disk number will still have different disk
report numbers. The first disk reported will have a disk
report number of 1.
2.Disk number (D4): This is the disk number field extracted
from the header. If the disk number is invalid or the
header unrecognizable this field is 9999.
3.Disk repeat (R2): Normally this is zero. It is possible
to find two disks for the same disk number in the same
disk group. The first repeat gets a repeat count of 1 for
its map file entries. If there are more than 100 disks
with the same number then extra digits will be printed
and the line sizes will be wrong. This is highly
unlikely.
4.Allocation Unit (A8): The AU within the disk where the
data was read. Note that this is different than the
extent number for physically addressed metadata since
extent 2 is near AU 113,000. If the disk is greater than
100 terabytes and the AU size is one megabyte, then this
field could exceed 8 digits.
5.File Number (F8): The ASM file that owns the extent. If
the number is less than 256 then this is ASM metadata or
an ASM registry. If this is physically addressed metadata
then the file number will be 00000000.
6.Indirect flag (I1): If this is a data extent for the file
then the indirect flag is 0. If this is an indirect
extent then this is 1.
7.Extent Number (E8): The physical extent number within the
file. This is the index in the file extent map that a
database instance would use to find this AU. If the file
was (two-way) mirrored then this is a primary extent if
the number is even, and a secondary copy if it is odd. If
this is an indirect extent then this is a value between 0
and 299 giving the index into the indirect extents. For
physically addressed metadata this is the extent within
the physically addressed metadata, not the AU within the
disk.
8.AU within extent (U2): Large extents are supported for
large files. Thus there could be multiple AU's dumped for
the same extent. Note that metadata files do not
currently use large extents so this only happens for user
file dumps to image files.
9.Block count (C5): The number of blocks copied to the
image file from the AU. A lot of space is saved by not
creating images of blocks that are just initialized
contents. This is particularly true for indirect extents
where most indirect extents will have only a few blocks
of extent pointers. If the extent is not dumped to the
image file then this is zero. The count is in ASM
metadata blocks, even if the file number is >256 and the
indirect flag is 0. This is normally 4K blocks, but could
be different in the future. With the -noimage option this
is always zero since no images are ever created.
10.Image File Sequence Number (S4): This is the NNNN
field of the image file name where blocks from the AU are
dumped. With the -noimage option this is always zero
since no image files are ever created.
11.Byte Offset in Image File (B10): This is the location
within the image file where the block images appear. It
is always a multiple of the ASM metadata block size.
Since the image file is always less than 2Gb this will
always fit in a 32 bit signed integer. Note that this
will be an offset to the end of the previously dumped AU
when the block count is zero. With the -noimage option
this is always zero since no images are ever created.
12.Corrupt Block Flag (X0): If any of the blocks in the
AU are corrupt, then the line will end with 'X'. Normally
this is a blank character so that the line ends in two
blanks.
This adds up to 56 digits, 12 letters, 11 blanks, and one
'\n' per line. This is a total of 79 characters including
the newline.
The map files are named "<group>.map" where <group> is the
disk group name in uppercase.
Report File
One report file is generated for every run of the utility
without the -directory option (except if -noreport is
specified). It is written to "report.txt" in the dump
directory. If -nodir is specified the report is written to
standard out instead of the dump directory name. Lines are
flushed to the report file as soon as they are generated so
tail -f can be used to monitor progress.
When AMDU is run with -print and -directory options then no
report is generated. Instead an existing report file must
be found and parsed. Information in the report file is used
instead of discovering the disks. The map file is used to
find the blocks to printout, and the block contents are
retrieved from the image files.
The report is divided into sections and subsections. Each
section begins with a title line. The title line has the
title centered and surrounded with '*'. There are always at
least three asterisks on either side of the title. A
subsection title is like a section title except that it is
surrounded with '-' rather than '*'.
Any errors reported by AMDU are also printed in the report
file. Warnings about unexpected conditions are printed in
upper case surrounded by "** ".
The following describes the sections in the report file.
AMDU Setting
The first lines describe the environment where the dump was
created. This includes the time when the report was
generated and the endianess of the data in the image files.
The host name, platform, and software version are also
included.
The following subsections describes all the arguments from
the command line: operations, disk selection, reading
control, and output control. This is a report of the
settings that result from the command line parsing, not a
copy of the command line.
The CORE package LRM is used to parse the command line
arguments. No dump directory or report file is generated if
there are argument parsing errors or if the user is only
requesting help. Command line errors will result in an exit
status of 1 rather than 0. Problems reading disks or
extracting a file will be reported on stderr and the report
file. The exit status will be 5 in accordance with LPM
standards.
Discovery
This section describes every disk returned by discovery.
There is one subsection for each disk. The title contains
the disk report number. This is followed by the information
from shallow discovery. If deep discovery is done for the
disk, then the results of deep discovery are reported next.
A warning message may indicate that a disk is being
ignored.
If the -noscan option is specified then this is the end of
the report. If the -noread option is given then this is the
end of the report and there is no deep discovery
information for any of the disks.
Sleeping for Heartbeat
Unless the -noheart option is given, a section header is
reported containing the time sleeping for heatbeat
detection. This makes it likely that any disks which
contain a PST of a mounted diskgroup will have a heartbeat
detected. The section has no lines other than the section
header.
Diskgroup Scan
There is one section for every disk group encountered by
deep discovery and referenced in either a -dump, -extract
or -print option ("-dump all" references all diskgroups
mentioned in any valid disk headers). The name of the disk
group is in the section header. This is followed by
information gathered about the diskgroup during deep. This
includes group wide parameters from the disk headers such
as AU size and creation time.
A disk scan subsection for each scanned disk in the
diskgroup follows the header. Disks that are ignored due to
deep discovery and/or command line options, do not have a
subsection. The subsection header includes the disk report
number. Some of the information from discovery is repeated
for convenience. This is reported before the scan begins.
Error messages and warnings, such as heartbeat detected,
may be reported during the scan. When the scan is complete
statistics from the scan are reported. This includes
information about data written to the map and image files.
Statistics such as space allocated and free are also
reported.
A group report subsection follows all the disk scan
subsections for the disks in the group. This subsection
gives cumulative statistics from all the disks in the disk
group.
Extracting File Sections
A section is reported for each file that is extracted. The
section header includes the diskgroup name and file number
from the -extract option. The name of the OS file created
by the extraction is on the first line of the section. Any
errors encountered are reported followed by statistics
about the extraction. If -directory is indicated, this info
will be writted to stdout.
End of Report
The last line of a report is the end of report section
header.
Printing Blocks
The -print option can be used to generate a formatted
printout of blocks from a diskgroup that is scanned in this
run of AMDU or from a dump directory created by a previous
run of AMDU. Use the -directory option to print from a
previous AMDU run.
Output Format
The formatted output is sent to standard out rather than to
a file. A section header, as in a report file, is printed
for each -print option on the command line. The section
header includes the block specification for the printout.
There is one subsection for each count in the block
specification. The subsection title is "BLOCK n OF c" where
n is the number of this block (starting at one), and c the
count of blocks in the block specification.
There may be multiple blocks on disk that match the
criteria for printing in one subsection. This may be due to
multiple disks appearing to be the same ASM disk or it may
be due to the normal mirroring of data. With the -fullscan
option it is common to encounter old stale blocks that
match the same criteria. A block description is printed for
each block that matches the printing criteria. When the
block contents are identical, then multiple block
descriptions are printed before the formatted printout of
the block. If the blocks are different then there may be
multiple formatted printouts in one subsection.
A block description consists of three lines. The first line
is a separator of all dots. The second line gives the
location of the block both as (disk, AU, block) and (file,
extent, block). The third line is the kfed command that
would create the same formatted output. This is useful for
constructing a kfed command to patch the block. It includes
the device name of the disk on the system where the dump
was created. If the AMDU directory was copied from another
system then the kfed command will have to be run on the
other system.
Block Specification
There are five different kinds of <block_spec>'s for
specifying a range of blocks to printout. They all start
with a diskgroup name. The name is case insensitive but it
is converted to uppercase. The name is followed by values
specified by '.', letter, number. The letter indicates the
meaning of the number and may be upper or lower case. The
number is a decimal number less than 2^32. The last value
may be an optional count of blocks to print using the
letter 'C'. So if the last field is ".C4" Then four blocks
will be printed starting at the first one specified by the
<block_spec>.
The five forms are as follows:
1.Report disk block: This form specifies a disk by it's
discovery order and a block by AU and block within AU.
The disk report number is always unique, but it is hard
to know the number unless you have already run AMDU and
seen at least the shallow discovery report. The advantage
of this form is that it never refers to multiple blocks
since AMDU gives every disk a unique disk report number.
<group>.N<report_number>.A<au_number>.B<block_number>
For example <block_spec> "DATA.N0001.A1.b0.c256" would
dump the entire PST AU from the first disk discovered
(providing it is in disk group DATA). Note that the
diskgroup name must match even though disk report numbers
are unique.
2.Group disk block: This is similar to report disk block
except that the ASM disk number is given rather than the
report disk number generated by AMDU. It is possible, but
a bad configuration, to see more than one disk with the
same ASM disk number for the same ASM disk group. If this
happens then this <block_spec> will refer to the blocks
on all the disks.
<group>.D<disk_number>.A<au_number>.B<block_number>
For example <block_spec> "Data.d2.A0.B0" would print the
disk header from disk 2 in diskgroup DATA. Also
<block_spec> "data.d2.a0.b256" and "data.d2.a1.b0" would
both print the PST header block of disk 2 in diskgroup
DATA (assuming an AU size of 1 MB and metadata block size
of 4096).
3.Extent file block: This form allows specification of a
block by a file physical extent number and block within
extent. When a file is mirrored there are two physical
extents for every virtual extents. This form allows
specification of only one mirror copy. It will support
printing of any file that is described by the map file.
However it is unlikely that a block dump will produce
anything but hex data for anything that is not an ASM
metadata file. Note that the block size is always the ASM
metadata block size no matter which file is being
printed. Note that any striping is not taken into account
when locating the block.
<group>.F<file_number>.X<extent_number>.B<block_number>
For example <block_spec> "flash.F3.X42.B0" would print
the secondary mirror copy of the checkpoint block of ACD
thread 2 in diskgroup FLASH. "Data.f3.x0.b0.c10752" would
print all the redo for thread 1 in diskgroup DATA (I hope
you have an empty file system)
4.Virtual file block: This form allows specification of a
block by its virtual block number within the file. Unless
this is an external redundancy disk group, all 3 copies
of the block are printed. If the copies are the same then
only one printout of the contents is generated. This form
is only allowed for ASM metadata files because the
redundancy can be determined from the diskgroup type, and
there is no striping.
<group>.F<file_number>.V<virtual_block_number>
For example <block_spec> "flash.F1.v2856" would print the
file directory block for file 2856 in diskgroup FLASH.
5.Extent map file block: This form allows specification of
a block in a files extent map. The first 60 extent
pointers are in the file directory the rest are in extent
map with 480 pointers per map block. For example
<block_spec> "flash.f2856.m0.c427" would print the entire
extent map for a 200GB file number 2856.
Command Line
AMDU uses the LRM package from CORE to parse its command
line. Thus it follows the LRM conventions. In particular it
follows the unix command style. The command line looks like
this:
admu [ <option> ... ]
Some options require specification of a number or string
while others are boolean flags that do not require a value.
Some options may appear multiple times to provide multiple
values. String options are specified as follows:
-keyword string
Number options are specified as:
-keyword number
Note that a number may end in K, k, M, m, G, or g to
indicate kilo (2^10), mega(2^20), or giga (2^30).
Boolean flags are specified as:
-keyword
Note that the CORE package LRM is used to parse the command
line options. This means you can specify options as
keyword=value, but unless you are very clever and
understand completely how LRM works, you will get
unexpected results such as ignored parameters. Stick to -
keyword syntax and you will be fine.
The options fall into four broad classes: operations, disk
selection, read control, and output control.
Operation
These parameters control the fundamental function of AMDU:
dumping metadata, extracting file contents, or printing
metadata blocks. If none of these are specified then only
discovery is performed (same as -noscan).
1.-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.
2.-extract <diskgroup>.<file>: This extracts the file (by name
or number) 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 and is required
if -directory is specified. 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.
ASM metadata files Number Name
FILE DIRECTORY 1 FILE
ASM DISK DIRECTORY 2 ASMDISK
ACTIVE CHANGE DIRECTORY 3 CHANGE
CONTINUING OPERATIONS DIRECTORY 4 CONTOP
TEMPLATE DIRECTORY 5 TEMPLATE
ALIAS DIRECTORY 6 ALIAS
AVD VOLUME FILE DIRECTORY 7 VOL
USED SPACE 8 USEDSPC
ATTRIBUTES DIRECTORY 9 ATTRIBUTES
ASM USER DIRECTORY 10 USER
ASM USER GROUP DIRECTORY 11 GROUP
STALENESS DIRECTORY 12 STALENESS
Files which have fixed numbers but are not ASM metadata files
STALE BITMAP SPACE REGISTRY 254 STALEREG
ORACLE CLUSTER REPOSITORY REGISTRY 255 OCR
3.-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
found 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>
Disk Selection
These parameters control the disk discover phase of
operations. They allow specification of which disks should
be scanned for AU's to dump. The operation options -dump, -
extract, and -print also limit scanning to disks in the
diskgroups specified by the options. The following options
can be specified to control how the disks are discovered
and scanned
1.-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.
2.-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.
3.-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.
4.-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. If block 0 is damaged, AMDU will try to read the
backup disk header. If this fails, and AMDU needs to
construct a working disk header, 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.
5.-directory <string>: This option completely eliminates
the discovery and disk scanning phases 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 FTP'ed from another machine. The
other machine may even be a different platform with a
different endianess.
Read Control
These parameters control which AU's on a disk are read and
how they are found. Every AU read from a -dump diskgroup is
dumped, unless the -noimage output option is set. Reading
still checks for I/O errors and corrupt blocks even if -
noimage is set. The default scanning algorithm is to look
at the allocation table and dump any extent that contains
ASM metadata according to its allocation table entry. The
registries are not considered metadata and are not dumped
by default. Registries are not modified through the ASM
buffer cache, and may not have ASM block headers on them.
If part of the AU contains metadata blocks that were never
modified, then the unmodified blocks are not dumped. The
most common case is the extra blocks in an indirect extent.
1.-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.
2.-ausize <bytes> -blksize <bytes>: Both of these options
must be set when -baddisks is set. They must both be a
power of 2. These sizes are required to scan a disk
looking for metadata, and it is normally read from the
disk header. The values apply to all disks that do not
have a valid header. The values from the disk header will
be used if a valid header is found.
3.-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 diskgroup "none" is normal or high
unless this option is given to specify external
redundancy.
4.-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.
5.-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)
6.-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.
7.-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.
8.-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.
9.-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.
10.-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.
Output control
Output control parameters change which output files are
created, where they are created, and how they are created.
The following options are supported.
1.-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.
2.-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.
3.-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).
4.-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.
5.-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.
6.-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. Required with -extract and -directory.
7.-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.
8.-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.
9.-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.
10.-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.
11.-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.
Inconsistencies
Since AMDU does not do all the checks required to mount a
diskgroup, it is possible for the disks to be inconsistent.
There may be missing disks or older stale disks. There
could be two different diskgroups with the same name. Since
the diskgroup may need crash recovery there could be
duplicate entries for the same file extent in the
allocation tables. Here are a list of the possible
inconsistencies and how they are dealt with
1.There could be two paths to the same disk. If two disks
have identical headers it is assumed they are the same
disk. The second disk is ignored and a message appears in
place of its deep discovery report.
2.There could be disks from two different diskgroups with
the same diskgroup name. An error message is given and
the disk group is not scanned. No files will be extracted
from the diskgroup and no metadata will be dumped or
printed. Use the exclude parameter to eliminate the disks
from one disk group.
3.There could be two disks in the same diskgroup with the
same disk number. This happens if a disk is dropped
force, another disk is added, and the old disk is
discovered by AMDU. Metadata will be dumped for both
disks. A file extraction will only look for extents on
the disk with the highest disk creation timestamp. The
other disk will be ignored even if it contains the only
copy of an extent.
4.There could be two AU's that are for the same file and
extent. This can happen if a relocation is incomplete.
For metadata dumping both extents are dumped. For file
extraction the contents will be compared. If they are the
same then there is no problem. If the contents differ
then the disk with the lowest disk report number will be
chosen. An error message will indicate the problem and
which disk was chosen.
5.With the -compare option the mirror copies of an extent
could differ. If this happens the primary extent will be
chosen. With high redundancy and a missing primary extent
the first secondary will be chosen. An error message will
be reported.