To connect to databases on read-only media, you can use the -RO parameter in a client connection string and when running certain PROUTIL database utilities. Unlike single-user sessions, multiple read-only connections can connect to the database simultaneously and run concurrently.

Read-only connections allow any number of connections at once, limited by the maximum number of users. Therefore, these connections are also valuable for fast diagnosis of database corruption issues, which prevent database startup. You can examine the failed database while it is stopped, identify problems, and fix the issues before restarting the database. Running diagnostic utilities concurrently on large databases reduces bottlenecks and expedites disaster recovery.

The following diagnostic utilities allow read-only connections:
A few restrictions apply to read-only connections:
  • To run concurrently, database utilities running read-only cannot connect when a database is open in single-user or multi-user mode.
  • Like single-user sessions, read-only connections allow no shared buffers, lock table, transaction table, server table, or user table.
  • Read-only connections open only the database (.db), and not the before-image log or the database log.
  • After a read-only connection connects to the database, it cannot switch back to the regular mode unless you end the connection and reconnect without specifying the -RO parameter.

To confirm that read operations are allowed on a read-only database, check its readiness state. See Check the database state.

For more about read-only connections, search the Progress Knowledge Base.