innochecksum

INNOCHECKSUM(1) MySQL Database System INNOCHECKSUM(1)

NAME
innochecksum - offline InnoDB file checksum utility

SYNOPSIS
innochecksum [options] file_name

DESCRIPTION
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 Options

innochecksum supports the following options. For options that refer to
page numbers, the numbers are zero-based.

o --help, -? Displays command line help. Example usage:

innochecksum --help

o --info, -I Synonym for --help. Displays command line help. Example
usage:

innochecksum --info

o --version, -V Displays version information. Example usage:

innochecksum --version

o --verbose, -v 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
...

o --count, -c Print a count of the number of pages in the file and
exit. Example usage:

innochecksum --count ../data/test/tab1.ibd

o --start-page=num, -s num Start at this page number. Example usage:

innochecksum --start-page=600 ../data/test/tab1.ibd

or:

innochecksum -s 600 ../data/test/tab1.ibd

o --end-page=num, -e num End at this page number. Example usage:

innochecksum --end-page=700 ../data/test/tab1.ibd

or:

innochecksum --p 700 ../data/test/tab1.ibd

o --page=num, -p num Check only this page number. Example usage:

innochecksum --page=701 ../data/test/tab1.ibd

o --strict-check, -C 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:

o If you do not specify the --strict-check option, innochecksum
validates against innodb, crc32 and none.

o If you specify the none option, only checksums generated by
none are allowed.

o If you specify the innodb option, only checksums generated by
innodb are allowed.

o If you specify the crc32 option, only checksums generated by
crc32 are allowed.

o --no-check, -n 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

o --allow-mismatches, -a The maximum number of checksum mismatches
allowed before innochecksum terminates. The default setting is 0.
If --allow-mismatches=N, where N>=0, N mismatches are permitted and
innochecksum terminates at N+1. When --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.

o --write=name, -w num 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:

o innodb: A checksum calculated in software, using the original
algorithm from InnoDB.

o crc32: A checksum calculated using the crc32 algorithm,
possibly done with a hardware assist.

o 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

o --page-type-summary, -S 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

o --page-type-dump, -D 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

o --log, -l 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

o - option. 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
Running innochecksum on Multiple User-defined Tablespace Files

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

Note
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
Running innochecksum on Multiple System Tablespace Files

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.

Note
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

This documentation is free software; you can redistribute it and/or
modify it only under the terms of the GNU General Public License as
published by the Free Software Foundation; version 2 of the License.

This documentation is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License along
with the program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA or see
http://www.gnu.org/licenses/.

SEE ALSO
For more information, please refer to the MySQL Reference Manual, which
may already be installed locally and which is also available online at
http://dev.mysql.com/doc/.

AUTHOR
Oracle Corporation (http://dev.mysql.com/).

MySQL 8.0 08/31/2023 INNOCHECKSUM(1)

innochecksum

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