Rds; Infiniband Hardware Architecture - HP 4X - DDR InfiniBand Mezzanine HCA Using Manual

RDS

The Reliable Datagram Sockets (RDS) is a low-overhead, low-latency, high-bandwidth transport
protocol that yields high performance for cluster interconnect-intensive environments such as Oracle
Database or Real Application Cluster (RAC). The RDS protocol offloads error-checking operations to
the InfiniBand fabric, freeing more CPU time for application processing.

InfiniBand hardware architecture

InfiniBand fabrics use high-speed, bi-directional serial interconnects between devices. Interconnect
bandwidth and distances are characteristics determined by the type of cabling and connections
employed. The bi-directional links contain dedicated send and receive lanes for full duplex operation.
For quad data rate (QDR) operation, each lane has a signaling rate of 10 Gbps. Bandwidth is
increased by adding more lanes per link. InfiniBand interconnect types include 1x, 4x, or 12x wide
full-duplex links (Figure 5)., The 4x is the most popular configuration and provides a theoretical full-
duplex QDR bandwidth of 80 (2 x 40) gigabits per second.
Figure 5. InfiniBand link types
Encoding overhead in the data transmission process limits the maximum data bandwidth per link to
approximately 80 percent of the signal rate. However, the switched fabric design of InfiniBand allows
bandwidth to grow or aggregate as links and nodes are added. Double data rate (DDR) and
especially quad data rate (QDR) operation increase bandwidth significantly (Table 1).
Table 1. InfiniBand interconnect bandwidth
SDR
Link Signal rate
1x 2.5 Gbps
4x 10 Gbps
12x 30 Gbps
1x Link
(1 send channel,
1 receive channel,
each using differential voltage or
fiber optic signaling)
DDR QDR
Signal rate Signal rate
5 Gbps 10 Gbps
20 Gbps 40 Gbps
60 Gbps 120 Gbps
4x Link
12x Link
8