Multiple CUBRID Instances

Yes. Multiple instances of CUBRID Server can be installed on the same machine.

Regarding the Alternative hosts in JDBC driver, they are intended to be used in HA (High-Availability) environment, when in cases of CUBRID Server failure the system could fail-over to stand-by servers. The following is the syntax for JDBC connection string which includes alternative hosts.

URL=jdbc:CUBRID:127.0.0.1:31000:db1:::?althosts=127.0.0.2:31000,127.0.0.3:31000&rctime=600&charset=utf-8

althosts parameter should be passed via the connection string. It can contain a list of IP address:Port tuples separated by comma. This will mean that if a server on 127.0.0.1:31000 has failed, after rctime (in seconds) the system will fail-over to the stand-by server at 127.0.0.2:31000. If this fails, then will try the next one, etc. JDBC will automatically handle the changes between servers.

For more information about HA configurations, see http://www.cubrid.org/manual/840/en/CUBRID%20HA.