One Derby instance for each Java Virtual Machine You could potentially have two instances of a system (JVM) running on the same machine at the same time. Each instance must run in a different JVM. Two separate instances of must not access the same database. Multiple JVMs accessingprohibition of single systemprohibition of

For example, in an embedded environment, an application that accesses databases starts up the local JDBC driver, which starts up an instance of . If you start another application, such as ij, and connect to the same database, severe database corruption can result. See .