The derby.replication.logBufferSize property specifies the size of the replication log buffers in bytes.
These buffers store the log on the master side before it is shipped to the slave. There is a total of 10 such buffers.
Large buffers increase memory usage but reduce the chance that the buffers will fill up (in turn increasing response time for transactions on the master, as described in the failure situation "The master Derby instance is not able to send log data to the slave at the same pace as the log is generated" in the topic "Replication failure handling" in the Derby Server and Administration Guide).
You can also use the properties derby.replication.minLogShippingInterval and derby.replication.maxLogShippingInterval to tune the rate at which the log is shipped from the master to the slave.
8192 (8 KB).
The maximum value is 1048576 (1 MB).
32768 bytes (32KB).
derby.replication.logBufferSize=65536
This property is static; if you change it while Derby is running, the change does not take effect until you reboot.