MySQL 5.6 Reference Manual Including MySQL NDB Cluster 7.3-7.4 Reference Guide Using Symbolic Links with Disk Data Objects

The performance of an NDB Cluster that uses Disk Data storage can be greatly improved by separating data node file systems from undo log files and tablespace data files and placing these on different disks. In early versions of NDB Cluster, there was no direct support for this in NDB Cluster, and it was necessary to achieve this separation using symbolic links as described later in this section. NDB Cluster 7.3 and later supports the data node configuration parameters FileSystemPathDD, FileSystemPathDataFiles, and FileSystemPathUndoFiles, which make the use of symbolic links for this purpose unnecessary. For more information about these parameters, see Disk Data file system parameters.

The procedure described in the remainder of this section is of historical interest only.

Each data node in the cluster creates a file system in the directory named ndb_node_id_fs under the data node's DataDir as defined in the config.ini file. In this example, we assume that each data node host has 3 disks, aliased as /data0, /data1, and /data2, and that the cluster's config.ini includes the following:

[ndbd default]
DataDir= /data0

Our objective is to place all Disk Data log files in /data1, and all Disk Data data files in /data2, on each data node host.


In this example, we assume that the cluster's data node hosts are all using Linux operating systems. For other platforms, you may need to substitute you operating system's commands for those shown here.

To accomplish this, perform the following steps: