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Specifies how to generate and verify the checksum stored in the disk blocks of InnoDB  tablespaces. The default value for innodb_checksum_algorithm  is crc32 . 

Versions of MySQL Enterprise Backup up to 3.8.0 do not support backing up tablespaces that use CRC32 checksums. MySQL Enterprise Backup adds CRC32 checksum support in 3.8.1, with some limitations. Refer to the MySQL Enterprise Backup 3.8.1 Change History for more information. 

The value innodb  is backward-compatible with earlier versions of MySQL. The value crc32  uses an algorithm that is faster to compute the checksum for every modified block, and to check the checksums for each disk read. It scans blocks 32 bits at a time, which is faster than the innodb  checksum algorithm, which scans blocks 8 bits at a time. The value none  writes a constant value in the checksum field rather than computing a value based on the block data. The blocks in a tablespace can use a mix of old, new, and no checksum values, being updated gradually as the data is modified; once blocks in a tablespace are modified to use the crc32  algorithm, the associated tables cannot be read by earlier versions of MySQL. 

The strict form of a checksum algorithm reports an error if it encounters a valid but non-matching checksum value in a tablespace. It is recommended that you only use strict settings in a new instance, to set up tablespaces for the first time. Strict settings are somewhat faster, because they do not need to compute all checksum values during disk reads. 

The following table shows the difference between the none , innodb , and crc32  option values, and their strict counterparts. none , innodb , and crc32  write the specified type of checksum value into each data block, but for compatibility accept other checksum values when verifying a block during a read operation. Strict settings also accept valid checksum values but print an error message when a valid non-matching checksum value is encountered. Using the strict form can make verification faster if all InnoDB  data files in an instance are created under an identical innodb_checksum_algorithm  value. 

## Table 15.26 Permitted innodb_checksum_algorithm Values 

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