Alpha processor: a little marvel

ONE YEAR AGO last month, Compaq announced its long-awaited and much-delayed AlphaServer GS-Series "Wildfire" enterprise server family. Despite making its debut nearly a year and a half later than Compaq originally anticipated, the new AlphaServer GS-Series proved to be a hit with installed base customers and new adopters alike. Compaq generated over $800M in GS-Series revenue in Y2K, and appears on track to rake in as much as $1.5B-$2B during 2001. As previously reported in SKC, a 1GHz GS-Series upgrade is slated for early July, and Compaq has been taking orders for the turbocharged Wildfire at a brisk pace.

As we've noted in the past, Compaq plans a series of system enhancements and upgrades that should enable the GS-Series to deliver a substantial performance improvement over the next several years. Next on the GS-Series agenda is the next-generation Alpha 21364 EV7 microprocessor. The first fully functional pass of the EV7 CPU and its companion IO7 chip taped out last two months ago-about six weeks ahead of schedule-and Compaq hopes to begin testing Pass One EV7 hardware this month.

While production-quality Pass Two and Pass Three EV7 parts are unlikely to debut before 2HCY02, Compaq has, for quite some time, touted the capabilities of the next-generation Alpha chip in a variety of public venues. What's more, the firm has started to open the kimono on its planned EV7-based platforms.

Based on information gleaned at recentOpenVMS Technical Forums, together with data we're accumulated on the EV7 architecture, we can finally shed some new light on the next generation of Compaq GS-Series enterprise servers and the silicon that will power them.

Inside EV7
The Alpha 21364 EV7 chip is based on the EV6 processor core and is likely to run at frequencies similar to EV68 parts. New with EV7-which will incorporate six times as many transistors as the 15M transistor EV6 chip-are four to fivefold increases in memory and cache bandwidth, a massive 1.75MB L2 cache, hardware lockstep support for fault-tolerant systems, and on-chip switches. The latter capability will allow Compaq to build large SMP systems without the crossbar switches and interconnect infrastructure required in current AlphaServers. While existing Alpha platforms incorporate a CPU, crossbar switch chipset, and an extensive I/O infrastructure, an EV7 module can consist of as little as one EV7 CPU, an IO7 I/O chip, and one or more RAMBUS DRAMS.

EV7's on-chip switching and "glueless SMP" support will allow Compaq to field Alpha systems composed of fewer, less costly components that can be linked together like Lego blocks to form large-scale SMP complexes based on a 2D mesh architecture. This approach dispenses with the QBB and Global Switch infrastructure found in current GS-Series enterprise servers.

Although it's possible to construct single-CPU EV7 systems, Compaq is likely to focus on integrated dual-processor modules as the basic building block for future large-scale Alpha systems. This 2P module will consist of a pair of EV7 CPUs with vapor-chamber heat risers, 20 RAMBUS card slots, voltage regulator cards, and server management daughtercards.

The Two Faces of EV-7
Leveraging the 2P module, Compaq plans to offer a pair of Alpha EV7-based platforms that target the telecom, and mainstream computing marketplaces respectively. The first system out the door is likely to be "Raptor," a dual-processor CompactPCI platform designed for the telecom marketplace. Consistent with Compaq's agreement to provide Alpha-based advanced switching computers for Ericsson's AXE-based next-generation wireless and wireline networks, Raptor may debut as a 2P EV68-and-Titan-based product that'll be field-upgradable to EV7 status.

Also leveraging the 2P module-albeit somewhat later, perhaps on third-pass EV7 silicon, will be the AlphaServer GS-Series "Marvel" enterprise server. Customers with existing GS-Series systems will be able to upgrade their systems to EV7 status by replacing GS-Series QBBs, Global Switches, and memory subsystems with up to 24 2P Marvel drawers. Such an upgrade would grow a GS320 to a 48-CPU EV7 configuration.

Compaq will focus its Marvel efforts on new systems, and SKC believes the best GS-Series-to-Marvel upgrade strategy involves clustering incumbent GS-Series servers with next-generation Marvels. New large-scale Marvel systems will be based on 8U drawers or building blocks containing 8 CPUs, memory, and hot-swap fans. Customers will be able to stack four 8P modules in a standard 2-meter rack; up to four racks can be linked together to form a 128-CPU Marvel server with up to 4TB of memory and over 1K PCI slots.

Thanks to the modular design of the Marvel architecture, the cost of growing a system from 8 to 128 CPUs will be essentially flat: a single 32-processor system should cost no more than four 8-CPU systems, and a full-blown 128-CPU system should cost no more than 16 8-CPU systems. Given the hefty pricing "speed bumps" that accompany GS80-to-GS160-to-GS320 upgrades-not to mention rival vendor upgrade paths-the Marvel value proposition will be very compelling in CY03. µ

Terry Shannon is the editor and publisher of Shannon knows Compaq