Tuning Global Cache - Expert Oracle RAC Performance Diagnostics and Tuning - page 383

RMS n
Oracle RAC Management Processes ( RMS n ) introduced in Oracle Database 11g Release 2 performs manageability tasks
for RAC tasks accomplished by an RMS n process when instances are added to the cluster.
RSMN
Remote Slave Monitor (RSMN) introduced in Oracle Database 11g Release 2 manages background slave process
creation and communication on remote instances. This background process manages the creation of slave processes
and the communication with their coordinators and peers. These background slave processes perform tasks on behalf
of a coordinating process running in another cluster instance.
PING
Interconnect Latency Measurement Process (PING) assesses the latencies associated with any two instances in the
cluster. Every few seconds, the process in one instance sends two messages to the target instance. One message
is of size 500 bytes and the second message if of size 8KB. Once the message is received by the target instance, it's
acknowledged indicating the health of the interconnect.
IPC0
IPC service background process (IPC0) is a new background process introduced in Oracle Database 12c Release 1.
It handles very high rates of incoming connect requests as well as completing reconfigurations to support basic
messaging and RDMA (remote direct memory access) primitives over several transports such as UDP (User Datagram
Protocol), RDS (Reliable Datagram Sockets), Infiniband, and RC (reliable connection).
LDDn
Global Enqueue Service Daemon Helper Slave (LDDn) introduced in Oracle Database 12c Release 1, are slave
processes spawned on demand by the LMDn process. These slaves help perform certain tasks when certain workloads
start creating performance bottlenecks.
Resource Availability
To manage the request for data blocks, Oracle needs buffers in its memory where requests and locks related to these
requests could be maintained. Such resources are global cache resources and maintained in the SGA of every instance
in the cluster. Figure 13-2 illustrates both global cache and global enqueue resource buffers maintained in the shared
pool and SGA.