[sci] sections in the
config.ini file explicitly define SCI
(Scalable Coherent Interface) connections between cluster nodes.
Using SCI transporters in MySQL Cluster is supported only when
the MySQL binaries are built using
path should point to a directory
that contains at a minimum
include directories containing SISCI
libraries and header files. (See
Section 5.5, “Using High-Speed Interconnects with MySQL Cluster” for more
information about SCI.)
In addition, SCI requires specialized hardware.
It is strongly recommended to use SCI Transporters only for communication between ndbd processes. Note also that using SCI Transporters means that the ndbd processes never sleep. For this reason, SCI Transporters should be used only on machines having at least two CPUs dedicated for use by ndbd processes. There should be at least one CPU per ndbd process, with at least one CPU left in reserve to handle operating system activities.
To identify a connection between two nodes it is necessary
to provide node identifiers for each of them, as
This identifies the SCI node ID on the first Cluster node
It is possible to set up SCI Transporters for failover between two SCI cards which then should use separate networks between the nodes. This identifies the node ID and the second SCI card to be used on the first node.
This identifies the SCI node ID on the second Cluster node
When using two SCI cards to provide failover, this parameter identifies the second SCI card to be used on the second node.
HostName2 parameters can be used to
specify specific network interfaces to be used for a given
SCI connection between two nodes. The values used for these
parameters can be hostnames or IP addresses.
Each SCI transporter has a shared memory segment used for communication between the two nodes. Setting the size of this segment to the default value of 1MB should be sufficient for most applications. Using a smaller value can lead to problems when performing many parallel inserts; if the shared buffer is too small, this can also result in a crash of the ndbd process.
A small buffer in front of the SCI media stores messages before transmitting them over the SCI network. By default, this is set to 8KB. Our benchmarks show that performance is best at 64KB but 16KB reaches within a few percent of this, and there was little if any advantage to increasing it beyond 8KB.
To trace a distributed message it is necessary to identify
each message uniquely. When this parameter is set to
Y, message IDs are transported over the
network. This feature is disabled by default in production
builds, and enabled in
This parameter is a boolean value, and is disabled by
Checksum is enabled,
checksums are calculated for all messages before they are
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
When more than this many unsent bytes are in the send buffer, the connection is considered overloaded. See Section 5.2.13, “Configuring MySQL Cluster Send Buffer Parameters”, for more information.