1# redo log from before MySQL 5.7.9 2# redo log from before MySQL 5.7.9, with corrupted log checkpoint 3# redo log from before MySQL 5.7.9, with corrupted log block 4# redo log from "after" MySQL 5.7.9, but with invalid header checksum 5# distant future redo log format, with valid header checksum 6# valid header, but old-format checkpoint blocks 7# valid header, valid checkpoint 1, all-zero (invalid) checkpoint 2, invalid block checksum 8# --innodb-force-recovery=6 (skip the entire redo log) 9# valid header, valid checkpoint 1, all-zero (invalid) checkpoint 2, invalid block number 10# --innodb-force-recovery=6 (skip the entire redo log) 11# Test a corrupted MLOG_FILE_NAME record. 12# valid header, valid checkpoint 1, all-zero (invalid) checkpoint 2 13# Test a corrupted MLOG_FILE_NAME record. 14# valid header, invalid checkpoint 1, valid checkpoint 2 15