Specifications
76 IBM Power 770 and 780 Technical Overview and Introduction
Table 2-23 compares Parallel SCSI to SAS attributes.
Table 2-23 Comparing Parallel SCSI to SAS
2.8.8 iSCSI adapters
iSCSI adapters in Power Systems provide the advantage of increased bandwidth through the
hardware support of the iSCSI protocol. The 1 Gigabit iSCSI TOE (TCP/IP Offload Engine)
PCI-X adapters support hardware encapsulation of SCSI commands and data into TCP, and
transports them over the Ethernet using IP packets. The adapter operates as an iSCSI TOE.
This offload function eliminates host protocol processing and reduces CPU interrupts. The
adapter uses a small form factor LC type fiber optic connector or a copper RJ45 connector.
Table 2-24 lists the orderable iSCSI adapters.
Table 2-24 Available iSCSI adapters
Items to compare Parallel SCSI SAS
Architecture Parallel, all devices connected to
shared bus
Serial, point-to-point, discrete
signal paths
Performance 320 MBps (Ultra320 SCSI),
performance degrades as devices
are added to shared bus
3 Gbps, scalable to 12 Gbps,
performance maintained as more
devices are added
Scalability 15 drives Over 16,000 drives
Compatibility Incompatible with all other drive
interfaces
Compatible with Serial ATA (SATA)
Max. cable length 12 meters total (must sum lengths
of all cables used on bus)
8 meters per discrete connection,
total domain cabling hundreds of
meters
Cable from factor Multitude of conductors adds bulk,
cost
Compact connectors and cabling
save space, cost
Hot pluggability No Yes
Device identification Manually set, user must ensure no
ID number conflicts on bus
Worldwide unique ID set at time of
manufacture
Termination Manually set, user must ensure
proper installation and
functionality of terminators
Discrete signal paths enable
device to include termination by
default
Feature
code
CCIN Adapter description Slot Size OS
support
#5713 573B 1 Gigabit iSCSI TOE PCI-X on Copper
Media Adapter
PCI-X Short A, i, L
#5714
a
a. Supported, but no longer orderable
573C 1 Gigabit iSCSI TOE PCI-X on Optical
Media Adapter
PCI-X A, i, L