Network messenger

Messenger is the Ceph network layer implementation. Both simple and async messenger types are supported.

The default messenger type is async. To change the messenger type, specify the ms_type configuration setting in the [global] section of the Ceph configuration file.

Note: For the async messenger, IBM supports the posix transport type, but does not currently support rdma or dpdk. By default, the ms_type setting in IBM Storage Ceph reflects async+posix, where async is the messenger type and posix is the transport type.

SimpleMessenger: The SimpleMessenger implementation uses TCP sockets with two threads per socket. Ceph associates each logical session with a connection. A pipe handles the connection, including the input and output of each message. While SimpleMessenger is effective for the posix transport type, it is not effective for other transport types such as rdma or dpdk.
AsyncMessenger: AsyncMessenger is the default messenger type. AsyncMessenger implementation uses TCP sockets with a fixed-size thread pool for connections, which should be equal to the highest number of replicas or erasure-code chunks. The thread count can be set to a lower value if performance degrades due to a low CPU count or a high number of OSDs per server.

Note: Other transport types, such as rdma and dpdk are not currently supported.

For more information about using on-wire encryption with the Ceph messenger version 2 protocol, see Ceph on-wire encryption.

For more information about asynchronous messenger options, see Network configuration options.