Using the read-only replica

You can perform all normal operations against your master server (p4 -p master:1666 command). To reduce the load on the master server, direct reporting (read-only) commands to the replica (p4 -p replica:1667 command). Because the replica is running in -M readonly -D readonly mode, commands that read both metadata and depot file contents are available, and reporting commands (such as p4 annotate, p4 changes, p4 filelog, p4 diff2, p4 jobs, and others) work normally. However, commands that update the server’s metadata or depot files are blocked.

Commands that update metadata

Some scenarios are relatively straightforward: consider a command such as p4 sync. A plain p4 sync fails, because whenever you sync your workspace, the Helix Core Server must update its metadata (the "have" list, which is stored in the db.have table). Instead, use p4 sync -p to populate a workspace without updating the have list:

$ p4 -p replica:1667 sync -p //depot/project/...@1234

This operation succeeds because it does not update the server’s metadata.

Some commands affect metadata in more subtle ways. For example, many Helix Server commands update the last-update time that is associated with a specification (for example, a user or client specification). Attempting to use such commands on replica servers produces errors unless you use the -o option. For example, p4 client (which updates the Update: and Access: fields of the client specification) fails:

$ p4 -p replica:1667 client replica_client
Replica does not support this command.

However, p4 client -o works:

$ p4 -p replica:1667 client -o replica_client
(client spec is output to STDOUT)

If a command is blocked due to an implicit attempt to write to the server’s metadata, consider workarounds such as those described above. (Some commands, like p4 submit, always fail, because they attempt to write to the replica server’s depot files; these commands are blocked by the -D readonly option.)

Using the Helix Broker to redirect commands

You can use the Helix Broker with a replica server to redirect read-only commands to replica servers. This approach enables all your users to connect to the same protocol:host:port setting (the broker). In this configuration, the broker is configured to transparently redirect key commands to whichever Helix Core Server is appropriate to the task at hand.

For an example of such a configuration, see the Knowledge Base article, "Using P4Broker to redirect read-only commands".