89294

Configuring MySQL Cluster Send Buffer Parameters

Formerly, the NDB kernel employed a send buffer whose size was fixed at 2MB for each node in the

cluster, this buffer being allocated when the node started. Because the size of this buffer could not

be changed after the cluster was started, it was necessary to make it large enough in advance to

accommodate the maximum possible load on any transporter socket. However, this was an inefficient

use of memory, sińce much of it often went unused, and could result in large amounts of resources

being wasted when scaling up to many API nodes.

This problem was eventually solved (in MySQL Cluster NDB 7.0) by employing a unified send buffer

whose memory is allocated dynamically from a pool shared by all transporters. This means that the

size of the send buffer can be adjusted as necessary. Configuration of the unified send buffer can

accomplished by setting the following parameters:

• TotalSendBuf ferMemory. This parameter can be set for all types of MySQL Cluster nodes—

that is, it can be set in the (ndbd ], (mgm ], and [ api) (or [ mysql ]) sections of the

config.ini

file. It represents the total amount of memory (in bytes) to be allocated by each node for which

it is set for use among all configured transporters. If set, its minimum is 256KB; the

maximum is

4294967039.