IBM Power System Series Manual page 156

Figure 46. PCIe3 12 GB Cache RAID SAS 6 Gb Adapter
To provide the highest bandwidth between two paired feature EJ0L adapters for the mirroring of cache
data and parity update footprints, two SAS Adapter-to-Adapter (AA) cables are required by default on the
third and fourth adapter ports (T2, T3) until maximum device quantity attachment is required. When all
connectors are attaching SAS drives, the communication between the adapter pair is performed through
the SAS fabric via the I/O drawers and cabling.
The FC EJ0L is a single wide, full-height, short adapter. Figure 46 on page 142 shows the FC EJ0L
adapter. Every FC EJ0L requires another FC EJ0L on this server, or on another server, which pairs with the
SAS RAID adapter and enables cache functionality and the other multi-initiator high availability (dual
storage IOA) functions. Best performance is achieved when multiple RAID sets are configured and
optimized under a pair of adapters in a high availability, multi-initiator RAID configuration (dual storage
IOA) which allows for an Active-Active mode of operation.
Systems running the AIX or Linux operating systems support either having both EJ0L features in the same
system or partition, or in two separate systems or partitions. Systems running the IBM i operating system
do not support the pairing of adapters on different servers or different partitions, so both the EJ0L
142 Power Systems: Managing PCIe adapters