- 17.3.2 MySQL Cluster Configuration Files
- 17.3.2.1 MySQL Cluster Configuration: Basic Example
- 17.3.2.2 Recommended Starting Configuration for MySQL Cluster
- 17.3.2.3 MySQL Cluster Connection Strings
- 17.3.2.4 Defining Computers in a MySQL Cluster
- 17.3.2.5 Defining a MySQL Cluster Management Server
- 17.3.2.6 Defining MySQL Cluster Data Nodes
- 17.3.2.7 Defining SQL and Other API Nodes in a MySQL Cluster
- 17.3.2.8 MySQL Cluster TCP/IP Connections
- 17.3.2.9 MySQL Cluster TCP/IP Connections Using Direct Connections
- 17.3.2.10 MySQL Cluster Shared-Memory Connections
- 17.3.2.11 SCI Transport Connections in MySQL Cluster
- 17.3.2.12 Configuring MySQL Cluster Send Buffer Parameters
MySQL Cluster attempts to use the shared memory transporter and
configure it automatically where possible.
[shm] sections in the
config.ini file explicitly define
shared-memory connections between nodes in the cluster. When
explicitly defining shared memory as the connection method, it
is necessary to define at least
NodeId1,
NodeId2, and
ShmKey. All other
parameters have default values that should work well in most
cases.
SHM functionality is considered experimental only. It is not officially supported in any current MySQL Cluster release, and testing results indicate that SHM performance is not appreciably greater than when using TCP/IP for the transporter.
For these reasons, you must determine for yourself or by using our free resources (forums, mailing lists) whether SHM can be made to work correctly in your specific case.
-
Effective Version Type/Units Default Range/Values NDB 7.3.0 numeric [none] ... Restart Type: N (See Section 17.3.3.4, “Other MySQL Cluster Configuration Parameters”, for information about restart types.)
Effective Version Type/Units Default Range/Values NDB 7.3.0 numeric [none] ... Restart Type: N (See Section 17.3.3.4, “Other MySQL Cluster Configuration Parameters”, for information about restart types.)
To identify a connection between two nodes it is necessary to provide node identifiers for each of them, as
NodeId1andNodeId2. -
Effective Version Type/Units Default Range/Values NDB 7.3.0 name or IP address [none] ... Restart Type: N (See Section 17.3.3.4, “Other MySQL Cluster Configuration Parameters”, for information about restart types.)
Effective Version Type/Units Default Range/Values NDB 7.3.0 name or IP address [none] ... Restart Type: N (See Section 17.3.3.4, “Other MySQL Cluster Configuration Parameters”, for information about restart types.)
The
HostName1andHostName2parameters can be used to specify specific network interfaces to be used for a given SHM connection between two nodes. The values used for these parameters can be hostnames or IP addresses. -
Effective Version Type/Units Default Range/Values NDB 7.3.0 unsigned [none] 0 - 4G Restart Type: N (See Section 17.3.3.4, “Other MySQL Cluster Configuration Parameters”, for information about restart types.)
When setting up shared memory segments, a node ID, expressed as an integer, is used to identify uniquely the shared memory segment to use for the communication. There is no default value.
-
Effective Version Type/Units Default Range/Values NDB 7.3.0 bytes 1M 64K - 4G Restart Type: N (See Section 17.3.3.4, “Other MySQL Cluster Configuration Parameters”, for information about restart types.)
Each SHM connection has a shared memory segment where messages between nodes are placed by the sender and read by the reader. The size of this segment is defined by
ShmSize. The default value is 1MB. -
Effective Version Type/Units Default Range/Values NDB 7.3.0 boolean false true, false Restart Type: N (See Section 17.3.3.4, “Other MySQL Cluster Configuration Parameters”, for information about restart types.)
To retrace the path of a distributed message, it is necessary to provide each message with a unique identifier. Setting this parameter to
Ycauses these message IDs to be transported over the network as well. This feature is disabled by default in production builds, and enabled in-debugbuilds. -
Effective Version Type/Units Default Range/Values NDB 7.3.0 boolean true true, false Restart Type: N (See Section 17.3.3.4, “Other MySQL Cluster Configuration Parameters”, for information about restart types.)
This parameter is a boolean (
Y/N) parameter which is disabled by default. When it is enabled, checksums for all messages are calculated before being placed in the send buffer.This feature prevents messages from being corrupted while waiting in the send buffer. It also serves as a check against data being corrupted during transport.
-
Effective Version Type/Units Default Range/Values NDB 7.3.0 unsigned [none] 0 - 4G Restart Type: N (See Section 17.3.3.4, “Other MySQL Cluster Configuration Parameters”, for information about restart types.)
When using the shared memory transporter, a process sends an operating system signal to the other process when there is new data available in the shared memory. Should that signal conflict with with an existing signal, this parameter can be used to change it. This is a possibility when using SHM due to the fact that different operating systems use different signal numbers.
The default value of
SigNumis 0; therefore, it must be set to avoid errors in the cluster log when using the shared memory transporter. Typically, this parameter is set to 10 in the[shm default]section of theconfig.inifile.
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