MySQL 8.0 Reference Manual Including MySQL NDB Cluster 8.0

22.4.22 ndb_redo_log_reader — Check and Print Content of Cluster Redo Log

Reads a redo log file, checking it for errors, printing its contents in a human-readable format, or both. ndb_redo_log_reader is intended for use primarily by NDB Cluster developers and Support personnel in debugging and diagnosing problems.

This utility remains under development, and its syntax and behavior are subject to change in future NDB Cluster releases.


Prior to NDB 7.2, this utility was named ndbd_redo_log_reader.

The C++ source files for ndb_redo_log_reader can be found in the directory /storage/ndb/src/kernel/blocks/dblqh/redoLogReader.

The following table includes options that are specific to the NDB Cluster program ndb_redo_log_reader. Additional descriptions follow the table. For options common to most NDB Cluster programs (including ndb_redo_log_reader), see Section 22.4.31, “Options Common to NDB Cluster Programs — Options Common to NDB Cluster Programs”.

Table 22.340 Command-line options for the ndb_redo_log_reader program

Format Description Added, Deprecated, or Removed


Print dump info

All NDB 8.0 releases


Print file descriptors only

All NDB 8.0 releases


Print usage information

All NDB 8.0 releases


Provide lap info, with max GCI started and completed

All NDB 8.0 releases

-mbyte #

Starting megabyte

All NDB 8.0 releases


Show only the first page header of every megabyte in the file

All NDB 8.0 releases


Do not check records for errors

All NDB 8.0 releases


Do not print records

All NDB 8.0 releases

-page #

Start with this page

All NDB 8.0 releases


Show page headers only

All NDB 8.0 releases

-pageindex #

Start with this page index

All NDB 8.0 releases


Bit-shifted dump

All NDB 8.0 releases


ndb_redo_log_reader file_name [options]

file_name is the name of a cluster redo log file. redo log files are located in the numbered directories under the data node's data directory (DataDir); the path under this directory to the redo log files matches the pattern ndb_nodeid_fs/D#/DBLQH/S#.FragLog. nodeid is the data node's node ID. The two instances of # each represent a number (not necessarily the same number); the number following D is in the range 8-39 inclusive; the range of the number following S varies according to the value of the NoOfFragmentLogFiles configuration parameter, whose default value is 16; thus, the default range of the number in the file name is 0-15 inclusive. For more information, see NDB Cluster Data Node File System Directory Files.

The name of the file to be read may be followed by one or more of the options listed here:

Like ndb_print_backup_file and ndb_print_schema_file (and unlike most of the NDB utilities that are intended to be run on a management server host or to connect to a management server) ndb_redo_log_reader must be run on a cluster data node, since it accesses the data node file system directly. Because it does not make use of the management server, this utility can be used when the management server is not running, and even when the cluster has been completely shut down.