Queue storage refers to the file storage that Broker Server uses to persist guaranteed documents and non-volatile Broker metadata (e.g., Broker definitions, document type definitions, client group definitions) to disk.

Queue storage consists of two files: a log file, which is a fixed-sized file that Broker can write data to quickly, and one or more storage files, into which data is ultimately stored using a logged-commit process. Queue storage is shared by all Brokers on a Broker Server.

Queue storage can be configured to operate in combined mode or separate mode. In combined mode, Broker metadata and run-time data are stored in the same log and storage files. In separate mode, the Broker uses two log files and two storage files. It stores metadata in one log/storage pair and run-time data in the other log/storage pair. When queue storage operates in separate mode, you can use the Broker Server's online backup utility to backup metadata while the Brokers on that server continue running.

As an administrator you can configure the size of the queue-storage files and monitor their usage. For information about managing queue storage, see Configuring Queue Storage.