# innochecksum

## 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 will cause InnoDB to
           deliberately shut down a running server, it can be preferable to
           use this tool rather than waiting for a server in production usage
           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.
    
           If checksum mismatches are found, you would normally restore the
           tablespace from backup or start the server and attempt to use
           **mariadb-dump** to make a backup of the tables within the tablespace.
    
           Invoke **innochecksum** like this:
    
               shell> **innochecksum [**_options_**]**_file_name_
    
           **innochecksum** supports the following options. For options that
           refer to page numbers, the numbers are zero-based.
    
           •   **-?, --help**
    
               Displays help and exits.
    
           •   **-a** _num_**, --allow-mismatches=#**
    
               Maximum checksum mismatch allowed before innochecksum
               terminates. Defaults to 0, which terminates on the first
               mismatch.
    
           •   **-c, --count**
    
               Print a count of the number of pages in the file.
    
           •   **-e** _num_**, --end-page=#**
    
               End at this page number.
    
           •   **-i, --per-page-details**
    
               Print out per-page detail information.
    
           •   **-I, --info**
    
               Synonym for **--help**.
    
           •   **-f, --leaf**
    
               Examine leaf index pages.
    
           •   **-l** _fn_**, --log=fn**
    
               Log output to the specified filename, fn.
    
           •   **-m** _num_**, --merge=#**
    
               Leaf page count if merge given number of consecutive pages.
    
           •   **-n, --no-check**
    
               Ignore the checksum verification. Until MariaDB 10.6, must be
               used with the --write option.
    
           •   **-p** _num_**, --page-num=#**
    
               Check only this page number.
    
           •   **-D** _name_**, --page-type-dump=name**
    
               Dump the page type info for each page in a tablespace.
    
           •   **-S, --page-type-summary**
    
               Display a count of each page type in a tablespace.
    
           •   **-s** _num_**, --start-page**
    
               Start at this page number.
    
           •   **-u, --skip-corrupt**
    
               Skip corrupt pages.
    
           •   **-C** _name_**, --strict-check=name**
    
               Specify the strict checksum algorithm. One of: crc32, innodb,
               none. If not specified, validates against innodb, crc32 and
               none. Removed in MariaDB 10.6.
    
           •   **-w** _name_**, --write=name**
    
               Rewrite the checksum algorithm. One of crc32, innodb, none. An
               exclusive lock is obtained during use. Use in conjunction with
               the -no-check option to rewrite an invalid checksum. Removed
               in MariaDB 10.6.
    
           •   **-v, --verbose**
    
               Verbose mode; print a progress indicator every five seconds.
    
           •   **-V, --version**
    
               Displays version information and exits.
    


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