This is easy to reproduce (tbin/sql will be uploaded later). 1. Make sure you have default-character-set=utf8 for clients, like this: [openxs@chief p5.6]$ cat ~/.my.cnf [client] default-character-set=utf8 2. Make sure there is no percona database. 3. Load data: [openxs@chief p5.6]$ bin/mysql --no-defaults -uroot test select count(*) from tbin; +----------+ | count(*) | +----------+ | 8192 | +----------+ 1 row in set (0.01 sec) mysql> exit Bye Try to use pt-table-checksum: [openxs@chief p5.6]$ pt-table-checksum u=root,P=3306,h=127.0.0.1 TS ERRORS DIFFS ROWS CHUNKS SKIPPED TIME TABLE 10-22T09:36:54 0 0 0 1 0 0.142 mysql.columns_priv 10-22T09:36:54 0 0 2 1 0 0.165 mysql.db 10-22T09:36:54 0 0 0 1 0 0.165 mysql.event 10-22T09:36:55 0 0 0 1 0 0.124 mysql.func 10-22T09:36:55 0 0 40 1 0 0.124 mysql.help_category 10-22T09:36:55 0 0 485 1 0 0.123 mysql.help_keyword 10-22T09:36:55 0 0 1090 1 0 0.123 mysql.help_relation 10-22T09:36:55 0 0 533 1 0 0.124 mysql.help_topic 10-22T09:36:55 0 0 18 1 0 0.165 mysql.innodb_index_stats 10-22T09:36:55 0 0 2 1 0 0.124 mysql.innodb_table_stats 10-22T09:36:55 0 0 0 1 0 0.123 mysql.ndb_binlog_index 10-22T09:36:56 0 0 0 1 0 0.133 mysql.plugin 10-22T09:36:56 0 0 0 1 0 0.131 mysql.proc 10-22T09:36:56 0 0 0 1 0 0.132 mysql.procs_priv 10-22T09:36:56 0 0 2 1 0 0.132 mysql.proxies_priv 10-22T09:36:56 0 0 0 1 0 0.141 mysql.servers 10-22T09:36:56 0 0 0 1 0 0.148 mysql.slave_master_info 10-22T09:36:56 0 0 0 1 0 0.149 mysql.slave_relay_log_info 10-22T09:36:57 0 0 0 1 0 0.140 mysql.slave_worker_info 10-22T09:36:57 0 0 0 1 0 0.123 mysql.tables_priv 10-22T09:36:57 0 0 0 1 0 0.125 mysql.time_zone 10-22T09:36:57 0 0 0 1 0 0.366 mysql.time_zone_leap_second 10-22T09:36:57 0 0 0 1 0 0.132 mysql.time_zone_name 10-22T09:36:57 0 0 0 1 0 0.124 mysql.time_zone_transition 10-22T09:36:58 0 0 0 1 0 0.124 mysql.time_zone_transition_type 10-22T09:36:58 0 0 6 1 0 0.130 mysql.user 10-22T09:36:58 Error checksumming table test.tbin: Error executing checksum query: Checksum query for table test.tbin caused MySQL error 1366: Level: Warning Code: 1366 Message: Incorrect string value: '\x82\\x82\\x82\...' for column 'lower_boundary' at row 4097 Query: REPLACE INTO `percona`.`checksums` (db, tbl, chunk, chunk_index, lower_boundary, upper_boundary, this_cnt, this_crc) SELECT ?, ?, ?, ?, ?, ?, COUNT(*) AS cnt, COALESCE(LOWER(CONV(BIT_XOR(CAST(CRC32(CONCAT_WS('#', `id`, `c1`, CONCAT(ISNULL(`id`), ISNULL(`c1`)))) AS UNSIGNED)), 10, 16)), 0) AS crc FROM `test`.`tbin` FORCE INDEX(`c1`) WHERE (((? IS NULL OR `c1` >= ?))) AND (((? IS NULL OR `c1` <= ?))) /*checksum chunk*/ 10-22T09:36:58 1 0 0 1 0 0.114 test.tbin Making columns for upper and lower boundary blobs helps.