HP N4000 (rp7400)

Quick Facts
Introduced	1999-2001
Period	Maturity (III)
CPU	1-8 PA-8500/ 1-8 PA-8600/ 1-8 PA-8700 360-750 MHz
Caches	1.5-2.25 MB L1
RAM	32 GB
Design	Stretch
Drives	2 SCSI
Expansion	12 PCI
Bandwidth	System 4.2 GB/s CPU 17 GB/s Mem 8.5 GB/s I/O 6.4 GB/s XBAR 15.3 GB/s
I/O	SCSI 3 serial 100E 100E console

The HP 9000 rp7400 were mid-range PA-RISC servers and the original HP 9000 N-Class N4000 from the turn of the century. The original N4000 (rp7400) is based the Stretch system architecture, also used in the L1500 and L3000 (rp5430/rp5470) servers. Later rp7405 and rp7410 servers were also labeled N4000 and feature a similar set of I/O options and expandability in basically the same chassis, with a completely different system architecture, the Cell.

N4000s were shipped in two models with different system boards: A3639A and A3639B. The N4000 that was later renamed as rp7400 was shipped with an even different mainboard with the model number A3639C.

Model	rp	Product	Introduced	Price
N4000		A3639A A3639B	1999	$48,000
	rp7400	A3639C	2001

The original N4000 (A3639A and A3639B) and later rp7400 (A3639C) are in fact different products, based on the same basic architecture but with differences relating to the type and number of processors.

System architecture

Processors

The rp7400 N4000 supports one to eight processors, designated by the [-36, -44, …, -7X] suffix. Not all of the earlier N4000 support the later processors and the maximum number of CPUs.

Model	Suffix	CPU	Speed	L1 Cache
N4000 A3639A	-36 -44	1-? PA-8500 1-? PA-8500	360 MHz 440 MHz	512/1024 KB on-chip 512/1024 KB on-chip
N4000 A3639B	-36 -44 -5X	1-? PA-8500 1-? PA-8500 1-? PA-8600	360 MHz 440 MHz 550 MHz	512/1024 KB on-chip 512/1024 KB on-chip 512/1024 KB on-chip
rp7400 A3639C	-36 -44 -5X -6X -7X	1-8 PA-8500 1-8 PA-8500 1-8 PA-8600 1-8 PA-8700 1-8 PA-8700	360 MHz 440 MHz 550 MHz 650 MHz 750 MHz	512/1024 KB on-chip 512/1024 KB on-chip 512/1024 KB on-chip 768/1536 KB on-chip 768/1536 KB on-chip

Itanium 2/IA64 processors were planned on the N4000 but apparently never offered.

Chipset

The rp7400 system is based on the Stretch chipset, used in the L1500 and L3000 (rp5430/rp5470) servers as well. Stretch has four main components:

Prelude memory controller, is the main crossbar of the system
Four DEW Runway converters, attach the processors to the main buses
Two IKE I/O controllers connect the PCI bridges via I/O channels
14 Elroy PCI bridges (LBAs) convert the IKE I/O to PCI buses

The rest of the system is implemented with common parts:

DEC 21142/43 Fast Ethernet controller
Dual-channel Symbios Logic 53C875 16-bit Ultra-Wide SCSI-2 controllers
Dual-channel Symbios Logic 53C896 Ultra2-Wide SCSI-3 controller

» View a system-level illustration (ASCII) of the N4000’s system/bus architecture.

System buses

The system bus architecture provides more bandwidth than could be used under practical circumstances. The designers probably counted on future CPU upgrades, such as Itanium.

Two Itanium system buses, 133 MHz, each 2.1 GB/s peak, 4.3 GB/s aggregate
Eight Runway+ CPU buses, each 2.1 GB/s peak, aggregate 17.0 GB/s
Four Memory buses, each 2.1 GB/s peak, aggregate 8.5 GB/s
24 I/O channels, each 133 MHz 265 MB/s, aggregate 6.4 GB/s
14 PCI-64/66 I/O buses for expansion slots
Three SCSI-3 Ultra2-Wide LVD main storage I/O buses, one for each internal drive and one for external devices

Memory

ECC SDRAM DIMMs
16 slots
256 MB, 512 MB, 1 GB and 2 GB modules supported
32 GB maximum

Expansion slots

Ten Twin-Turbo PCI 64-bit/66 MHz slots, each on an independent PCI bus, each connected via two I/O links/ropes (aggregate 530 MB/s), hot-plug capable
Two Turbo PCI 64-bit/66 MHz slots, each on an independent PCI bus, each connected via one I/O link/rope (265 MB/s), hot-plug capable (one of these two Turbo slots is reserved for Core I/O LAN/SCSI)
All slots keyed for 5.0 V (support either 5.0 V or universal PCI cards)

Storage

Two internal Ultra SCSI LVD 3.5″ drives with SCA connector, hot-pluggable

External ports

68-pin VHDCI Ultra LVD external SCSI
Three serial RS232C DB9 (local console, remote console, general purpose) via a DB25 M cable
10/100 Mbit Ethernet TP/RJ45
10/100 Mbit Ethernet TP/RJ45 LAN console

Operating systems

HP-UX: 64-bit 11.00, 11i v1, 11i v2 and 11i v3
Linux

Benchmarks

Model	SPEC2000, int	SPEC2000, fp	SPEC2000 rate, int	SPEC2000 rate, fp
N4000-6X rp7400	493	489	5.7 2-CPU: 11.3 4-CPU: 22.1 8-CPU: 42.6	5.7 2-CPU: 10.4 4-CPU: 19.3 8-CPU: 30.5
N4000-7X rp7400	551	524	6.4 2-CPU: 12.5 4-CPU: 24.6 8-CPU: 46.7	6.1 2-CPU: 11.0 4-CPU: 20.5 8-CPU: 32.1

References

Manuals

rp7400 Hardware Manual Hewlett-Packard Company (May 2002)
hp server rp7400 system architecture and design guide, Hewlett-Packard Company (February 2002, product number 5981-0154EN) (URL gone)

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