For 24/7 availability of backend database, High Availability a.k.a Database Mirroring would be a best option based on your description.
In SQL Anywhere 11, HA architecture typically comprise of Arbiter, Primary, and Mirror Server. Arbiter server will play a role in determining which server should act as Primary/Mirror server.
Database that runs in Primary server will be an "Active" backend database, where all the changes(Update,Insert, Delete) and reading of the content in database will be available. Mirror Server will host database in read-only mode, where only SELECT statement can be performed.
For example, client application can connect to Mirror Database Server to view the data, but when changes of data (i.e. updating the record of existing contact information from Application) are made from the application, then the application will speak to Primary Database to update the changes. After changes have been made on Primary Database server, comitted transaction will be synchronized over to the Mirror Database Server. So, when Primary Server goes down for an unexpected reason (i.e power shutdown from Primary Server), Mirror Server will negotiate will Arbiter server to act as a new Primary Server, which will contain exact copy of Primary Database(as long as latest transaction was fully comitted to Mirror before Primary Server went down).
Be considerate about which database mirroring mode (i.e. Asynchronous vs Synchronous) you want to use. Failover procedure is very different with these two modes.