MySQL 8.0 Reference Manual Including MySQL NDB Cluster 8.0
innochecksum prints checksums for
InnoDB files. This tool reads an
InnoDB tablespace file, calculates the
checksum for each page, compares the calculated checksum to the
stored checksum, and reports mismatches, which indicate damaged
pages. It was originally developed to speed up verifying the
integrity of tablespace files after power outages but can also
be used after file copies. Because checksum mismatches cause
InnoDB to deliberately shut down a running
server, it may be preferable to use this tool rather than
waiting for an in-production server to encounter the damaged
pages.
innochecksum cannot be used on tablespace
files that the server already has open. For such files, you
should use CHECK TABLE to check
tables within the tablespace. Attempting to run
innochecksum on a tablespace that the server
already has open results in an Unable to lock
file error.
If checksum mismatches are found, restore the tablespace from backup or start the server and attempt to use mysqldump to make a backup of the tables within the tablespace.
Invoke innochecksum like this:
innochecksum [options]file_name
innochecksum supports the following options. For options that refer to page numbers, the numbers are zero-based.
--help,
-?
| Command-Line Format | --help |
|---|---|
| Type | Boolean |
| Default Value | false |
Displays command line help. Example usage:
innochecksum --help
--info,
-I
| Command-Line Format | --info |
|---|---|
| Type | Boolean |
| Default Value | false |
Synonym for --help.
Displays command line help. Example usage:
innochecksum --info
--version,
-V
| Command-Line Format | --version |
|---|---|
| Type | Boolean |
| Default Value | false |
Displays version information. Example usage:
innochecksum --version
--verbose,
-v
| Command-Line Format | --verbose |
|---|---|
| Type | Boolean |
| Default Value | false |
Verbose mode; prints a progress indicator to the log file
every five seconds. In order for the progress indicator to
be printed, the log file must be specified using the
--log option. To turn on
verbose mode, run:
innochecksum --verbose
To turn off verbose mode, run:
innochecksum --verbose=FALSE
The --verbose option and
--log option can be specified at the same
time. For example:
innochecksum --verbose --log=/var/lib/mysql/test/logtest.txt
To locate the progress indicator information in the log file, you can perform the following search:
cat ./logtest.txt | grep -i "okay"
The progress indicator information in the log file appears similar to the following:
page 1663 okay: 2.863% done page 8447 okay: 14.537% done page 13695 okay: 23.568% done page 18815 okay: 32.379% done page 23039 okay: 39.648% done page 28351 okay: 48.789% done page 33023 okay: 56.828% done page 37951 okay: 65.308% done page 44095 okay: 75.881% done page 49407 okay: 85.022% done page 54463 okay: 93.722% done ...
--count,
-c
| Command-Line Format | --count |
|---|---|
| Type | Base name |
| Default Value | true |
Print a count of the number of pages in the file and exit. Example usage:
innochecksum --count ../data/test/tab1.ibd
--start-page=,
num-s
num
| Command-Line Format | --start-page=# |
|---|---|
| Type | Numeric |
| Default Value | 0 |
Start at this page number. Example usage:
innochecksum --start-page=600 ../data/test/tab1.ibd
or:
innochecksum -s 600 ../data/test/tab1.ibd
--end-page=,
num-e
num
| Command-Line Format | --end-page=# |
|---|---|
| Type | Numeric |
| Default Value | 0 |
| Minimum Value | 0 |
| Maximum Value | 18446744073709551615 |
End at this page number. Example usage:
innochecksum --end-page=700 ../data/test/tab1.ibd
or:
innochecksum --p 700 ../data/test/tab1.ibd
--page=,
num-p
num
| Command-Line Format | --page=# |
|---|---|
| Type | Integer |
| Default Value | 0 |
Check only this page number. Example usage:
innochecksum --page=701 ../data/test/tab1.ibd
--strict-check,
-C
| Command-Line Format | --strict-check=algorithm |
|---|---|
| Type | Enumeration |
| Default Value | crc32 |
| Valid Values |
|
Specify a strict checksum algorithm. Options include
innodb, crc32, and
none.
In this example, the innodb checksum
algorithm is specified:
innochecksum --strict-check=innodb ../data/test/tab1.ibd
In this example, the crc32 checksum
algorithm is specified:
innochecksum -C crc32 ../data/test/tab1.ibd
The following conditions apply:
If you do not specify the
--strict-check
option, innochecksum validates
against innodb,
crc32 and none.
If you specify the none option, only
checksums generated by none are
allowed.
If you specify the innodb option,
only checksums generated by innodb
are allowed.
If you specify the crc32 option, only
checksums generated by crc32 are
allowed.
--no-check,
-n
| Command-Line Format | --no-check |
|---|---|
| Type | Boolean |
| Default Value | false |
Ignore the checksum verification when rewriting a checksum.
This option may only be used with the
innochecksum
--write option. If the
--write option is not
specified, innochecksum terminates.
In this example, an innodb checksum is
rewritten to replace an invalid checksum:
innochecksum --no-check --write innodb ../data/test/tab1.ibd
| Command-Line Format | --allow-mismatches=# |
|---|---|
| Type | Integer |
| Default Value | 0 |
| Minimum Value | 0 |
| Maximum Value | 18446744073709551615 |
The maximum number of checksum mismatches allowed before
innochecksum terminates. The default
setting is 0. If
--allow-mismatches=N,
where N>=0N mismatches are permitted and
innochecksum terminates at
N+1--allow-mismatches is set to 0,
innochecksum terminates on the first
checksum mismatch.
In this example, an existing innodb
checksum is rewritten to set
--allow-mismatches to 1.
innochecksum --allow-mismatches=1 --write innodb ../data/test/tab1.ibd
With --allow-mismatches set to 1, if
there is a mismatch at page 600 and another at page 700 on a
file with 1000 pages, the checksum is updated for pages
0-599 and 601-699. Because
--allow-mismatches is set to 1, the
checksum tolerates the first mismatch and terminates on the
second mismatch, leaving page 600 and pages 700-999
unchanged.
--write=,
name-w
num
| Command-Line Format | --write=algorithm |
|---|---|
| Type | Enumeration |
| Default Value | crc32 |
| Valid Values |
|
Rewrite a checksum. When rewriting an invalid checksum, the
--no-check option must
be used together with the --write option.
The --no-check option
tells innochecksum to ignore verification
of the invalid checksum. You do not have to specify the
--no-check option if
the current checksum is valid.
An algorithm must be specified when using the
--write option.
Possible values for the --write option are:
innodb: A checksum calculated in
software, using the original algorithm from
InnoDB.
crc32: A checksum calculated using
the crc32 algorithm, possibly done
with a hardware assist.
none: A constant number.
The --write option rewrites entire pages to
disk. If the new checksum is identical to the existing
checksum, the new checksum is not written to disk in order
to minimize I/O.
innochecksum obtains an exclusive lock
when the --write option is used.
In this example, a crc32 checksum is
written for tab1.ibd:
innochecksum -w crc32 ../data/test/tab1.ibd
In this example, a crc32 checksum is
rewritten to replace an invalid crc32
checksum:
innochecksum --no-check --write crc32 ../data/test/tab1.ibd
| Command-Line Format | --page-type-summary |
|---|---|
| Type | Boolean |
| Default Value | false |
Display a count of each page type in a tablespace. Example usage:
innochecksum --page-type-summary ../data/test/tab1.ibd
Sample output for --page-type-summary:
File::../data/test/tab1.ibd
================PAGE TYPE SUMMARY==============
#PAGE_COUNT PAGE_TYPE
===============================================
2 Index page
0 Undo log page
1 Inode page
0 Insert buffer free list page
2 Freshly allocated page
1 Insert buffer bitmap
0 System page
0 Transaction system page
1 File Space Header
0 Extent descriptor page
0 BLOB page
0 Compressed BLOB page
0 Other type of page
===============================================
Additional information:
Undo page type: 0 insert, 0 update, 0 other
Undo page state: 0 active, 0 cached, 0 to_free, 0 to_purge, 0 prepared, 0 other
--page-type-dump,
-D
| Command-Line Format | --page-type-dump=name |
|---|---|
| Type | String |
| Default Value | [none] |
Dump the page type information for each page in a tablespace
to stderr or stdout.
Example usage:
innochecksum --page-type-dump=/tmp/a.txt ../data/test/tab1.ibd
--log,
-l
| Command-Line Format | --log=path |
|---|---|
| Type | File name |
| Default Value | [none] |
Log output for the innochecksum tool. A
log file name must be provided. Log output contains checksum
values for each tablespace page. For uncompressed tables,
LSN values are also provided. The
--log replaces the
--debug option, which was available in
earlier releases. Example usage:
innochecksum --log=/tmp/log.txt ../data/test/tab1.ibd
or:
innochecksum -l /tmp/log.txt ../data/test/tab1.ibd
Specify the - option to read from
standard input. If the - option is
missing when “read from standard in” is
expected, innochecksum prints
innochecksum usage information indicating
that the “-” option was omitted. Example
usages:
cat t1.ibd | innochecksum -
In this example, innochecksum writes the
crc32 checksum algorithm to
a.ibd without changing the original
t1.ibd file.
cat t1.ibd | innochecksum --write=crc32 - > a.ibd
The following examples demonstrate how to run
innochecksum on multiple user-defined
tablespace files (.ibd files).
Run innochecksum for all tablespace
(.ibd) files in the “test”
database:
innochecksum ./data/test/*.ibd
Run innochecksum for all tablespace files
(.ibd files) that have a file name starting
with “t”:
innochecksum ./data/test/t*.ibd
Run innochecksum for all tablespace files
(.ibd files) in the
data directory:
innochecksum ./data/*/*.ibd
Running innochecksum on multiple user-defined tablespace files is not supported on Windows operating systems, as Windows shells such as cmd.exe do not support glob pattern expansion. On Windows systems, innochecksum must be run separately for each user-defined tablespace file. For example:
innochecksum.exe t1.ibd innochecksum.exe t2.ibd innochecksum.exe t3.ibd
By default, there is only one InnoDB system
tablespace file (ibdata1) but multiple
files for the system tablespace can be defined using the
innodb_data_file_path option.
In the following example, three files for the system tablespace
are defined using the
innodb_data_file_path option:
ibdata1, ibdata2, and
ibdata3.
./bin/mysqld --no-defaults --innodb-data-file-path="ibdata1:10M;ibdata2:10M;ibdata3:10M:autoextend"
The three files (ibdata1,
ibdata2, and ibdata3)
form one logical system tablespace. To run
innochecksum on multiple files that form one
logical system tablespace, innochecksum
requires the - option to read tablespace
files in from standard input, which is equivalent to
concatenating multiple files to create one single file. For the
example provided above, the following
innochecksum command would be used:
cat ibdata* | innochecksum -
Refer to the innochecksum options information for more information about the “-” option.
Running innochecksum on multiple files in the same tablespace is not supported on Windows operating systems, as Windows shells such as cmd.exe do not support glob pattern expansion. On Windows systems, innochecksum must be run separately for each system tablespace file. For example:
innochecksum.exe ibdata1 innochecksum.exe ibdata2 innochecksum.exe ibdata3