Oracle 5.0 Reference Manual page 1593

The default heartbeat interval is 1500 milliseconds (1.5 seconds). This parameter must not be
changed drastically and should not vary widely between nodes. If one node uses 5000 milliseconds
and the node watching it uses 1000 milliseconds, obviously the node will be declared dead very
quickly. This parameter can be changed during an online software upgrade, but only in small
increments.
See also Network communication and
•
HeartbeatIntervalDbApi
Effective Version
MySQL 5.0.0
Restart Type: N
Each data node sends heartbeat signals to each MySQL server (SQL node) to ensure that it remains
in contact. If a MySQL server fails to send a heartbeat in time it is declared "dead," in which case all
ongoing transactions are completed and all resources released. The SQL node cannot reconnect
until all activities initiated by the previous MySQL instance have been completed. The three-
heartbeat criteria for this determination are the same as described for HeartbeatIntervalDbDb.
The default interval is 1500 milliseconds (1.5 seconds). This interval can vary between individual
data nodes because each data node watches the MySQL servers connected to it, independently of
all other data nodes.
For more information, see
•
TimeBetweenLocalCheckpoints
Effective Version
MySQL 5.0.0
Restart Type: N
This parameter is an exception in that it does not specify a time to wait before starting a new local
checkpoint; rather, it is used to ensure that local checkpoints are not performed in a cluster where
relatively few updates are taking place. In most clusters with high update rates, it is likely that a new
local checkpoint is started immediately after the previous one has been completed.
The size of all write operations executed since the start of the previous local checkpoints is added.
This parameter is also exceptional in that it is specified as the base-2 logarithm of the number of 4-
byte words, so that the default value 20 means 4MB (4 × 2
8MB, and so on up to a maximum value of 31, which equates to 8GB of write operations.
All the write operations in the cluster are added together. Setting
TimeBetweenLocalCheckpoints
continuously without pause, independent of the cluster's workload.
•
TimeBetweenGlobalCheckpoints
Effective Version
MySQL 5.0.0
Restart Type: N
MySQL Cluster Configuration Files
latency.
Type/Units
milliseconds
Network communication and
Type/Units
number of 4-byte
words, as a base-2
logarithm
to 6 or less means that local checkpoints will be executed
Type/Units
milliseconds
1573
Default
1500
latency.
Default
20
20
) of write operations, 21 would mean
Default
2000
Range/Values
100 - 4G
Range/Values
0 - 31
Range/Values
10 - 32000