You can monitor the IO-operations of db4o to find out more about the runtime behavior of your application.
In order to monitor the IO activities of db4o you need to configure the IO monitoring support.
configuration.common().add(new IOMonitoringSupport());
BytesReadPerSecond: Tells you how many bytes are read per second from the disk.
BytesWrittenPerSecond: Tells you how many bytes are written to disk per second.
ReadsPerSecond: Tells how many read requests are issues per second.
SyncsPerSecond: Tells you how many sync-operations are done per second. The sync-operation is a part of the commit-process. I forces the runtime and operating system to flush all buffers to the disk to ensure that the data are safely stored. The sync operation is normally a costly operation, since it need to wait on the physical disk to finish all write operations
.WritesPerSecond: Tells you how may write requests are issued per second.