Tricord: A Mainframe’s Little Sibling

PowerFrame Enterprise Servers

The Tricord Enterprise Servers are mighty big boxes. They're so big that,for shipping, they require specially designed crates with padded feet.

In each server's almost 4' tall cabinet, you can cram eight CPUs, up to3.25GB of main memory, and nine half-height drives. The interior is shaped toduct air past critical high-heat components, and three redundant power supplieswith 12-volt fans in each module pull air through. Still, wherever you set upthe Tricord server, make sure you have adequate cooling, because these unitsgenerate a lot of heat. A systems engineer accompanies each new system to helpset up and make sure the environment can handle the server.

Big Box, Big Features
The Tricord PowerFrame is not your typical PC server. It almost classifiesas a mainframe or minicomputer--only it consists of standard PC and Intelcomponents.

With starting prices of $70,000 for these machines, Tricord does not aim atthe small workgroup server market. Instead, typical installations are forenterprise and mission-critical applications (such as Internet ServiceProviders--ISPs), where fault tolerance and availability are key issues. As areflection of this focus, Windows NT is the operating system of choice for morethan 20% of Tricord's total new system sales.

The PowerFrame can hold up to eight 166MHz Pentium CPUs (NT 3.51 and 4.0both scale up to four CPUs right out of the box, but an OEM version of NT isnecessary if you want to run five to eight CPUs), each with its own 2MB Level 2cache module. The CPU-to-memory bus is part of the main 64-bit/ 33MHz systembus, which Tricord has dubbed the PowerBus. The PowerBus can reach267MB-per-second (MBps) transfer rates. This bus also couples the CPU and CacheSubsystem (CCS, which uses its own 64-bit/66MHz internal data bus) to the othermajor system components. Each board holds two CPUs, and a system can have up tofour CCS modules. Of the 10 total slots on the PowerFrame I reviewed, five aretaken by the Intelligent Communications Subsystem (the ATM PowerLink, anoptional 155Mbits-per-second--Mbps--fiber-optic ATM interface with its ownprocessing hardware), the Intelligent Storage Subsystem (ISS, multichannel SCSIbuses), the Main Memory Subsystem (MMS), the PCI Bridge Subsystem (PBS, two PCIbuses, one EISA bus, one peripheral bus), and the Intelligent ManagementSubsystem (IMS, hardware monitoring and management). This architecture lets eachsubsystem arbitrate its bus usage via the System Bus Arbiter, with buslocking by the active device. This approach avoids wasting valuable timepolling other subsystems.

All components except the ATM PowerLink are standard. A base configurationincludes one CCS, one ISS board, the MMS (with the amount of memory you need),the PBS, and the IMS. Each CCS board (you can have up to four) holds one or two166MHz Pentium CPUs with cache. The necessary subsystems take five slots, andyou can fill five other slots in any combination of CCS and ISS boards. The CCSis designed for NT's symmetrical multiprocessing (SMP--although the CCS alsosupports asymmetrical multiprocessing for other OSs). The large, high-speedStatic RAM (SRAM) Level 2 cache dedicated to each CPU significantly boosts theperformance of multithreaded and SMP-enabled, 32-bit NT applications such asdatabases (SQL Server, Oracle Server) and messaging (Exchange, Notes). ThePowerFrame's ability to use up to eight CPUs makes it a strong contender inenterprise NT environments where scaleability to high-end applications and heavyuser loads are important.

The ISS is Tricord's primary claim to fame, and the PowerFrame can supportup to six of these four-channel, fast-and-wide-and-deep, differential SCSI-2controllers (two-channel versions are also available). Deep SCSI uses four bitsfor device addressing instead of three, so one ISS controller card can addressup to 60 drives, with 15 drives on each channel (the last address is reservedfor the controller). One PowerFrame server can support up to 201 drives, so youcan have up to 2.1TB of disk storage with today's technology! The ISS ishardware accelerated for RAID levels 0, 1, 4, 5, and 10 (mirrored stripe sets,a.k.a. RAID 6), with disk hot-sparing (the SCSI backplane supports diskhot-swapping) and background disk rebuilding after failure and replacement. (Formore on performance under different RAID levels, see the sidebar, "RAIDPerformance and NT: Configuring an Enterprise Server.") The ISS boardincludes a battery-backed 8MB controller cache, so if system power fails, youdon't lose crucial data, even if it wasn't written to disk. Also, if thecontroller fails and the system goes offline, you can remove the card, transferthe cache module to a new controller card, reinstall it, and restart the systemto begin recovery procedures. You can be confident that data not already flushedfrom the cache out to disk was not lost (this capability doesn't include data inmain memory).

The PowerFrame's MMS can address up to 3.25GB of main Error-Correcting Code(ECC) DRAM memory. Unfortunately, Tricord chose to build proprietary memorymodules rather than use off-the-shelf components. This approach raises the priceof upgrading your system but has the advantage of improving performance withlarger SIMM capacities than the industry standard--a 256MB single module is onthe way. The MMS uses a 128-bit data path in parallel interleave (one 32-bitword from each module in a four-SIMM bank), and you can mix SIMM sizes if eachbank is consistent (upgrade in groups of four).

The PBS serves as the conduit for all other peripherals such as networkinterface cards, modems, video, and keyboard. The eight physical expansion slotssupport any combination of PCI or EISA cards. All slots are bus-master capable.The PBS has dual-PCI buses (32-bit, 33MHz for 132MBps) bridged to a 32-bit EISAbus (33MBps). An integrated SVGA graphics adapter is incorporated on the PCI bus(1MB VRAM) with an 8-bit I/O peripheral bus for parallel, serial, floppy, andkeyboard/ mouse. The PBS fully supports plug-and-play PCI and ISA cards for whenNT has the appropriate drivers. But be aware that placing old and slow 8-bit or16-bit cards on the high-speed PCI or EISA buses can drag down systemperformance significantly. Because the system has to service interrupts andtransfer data at the speed of the slowest component on the bus, the systemreduces the speed of all cards to match: Putting an old NE2000 NIC in yoursystem will hurt your overall system performance. The moral of the story is touse cards designed for the task instead of using whatever's lying around (and ifyou're spending $100,000 on a server, why skimp on a $300 network card?).

Finally, the IMS offers everything from gathering system bus usagestatistics to remotely managing server reboots. The IMS's two components are theboard in the server (the Intelligent Management Processor--IMP) and themanagement software. The board is NiCad battery backed for up to 85 hours ofserver downtime. During such downtime, the board can dial out for administratoralerts, store critical last-error information, report the server's last-knownand current status, and support dial-in management. The board has a built-in14.4Kbits-per-second (Kbps) modem, 512KB of SRAM holding CPU code and data, 8KBof configuration data memory, 256KB of flash memory for runtime firmware andboot code, and connections to power, cooling, and temperature sensing systems.Because the IMS board sits on the main PowerBus, it can monitor system activitysuch as bus utilization and disk and processor usage.

The IMS management software (as you see in Screen 1) can run on the serveror on a remote station (Windows 3.11 or later) via direct LAN connection ordial-up and can access any Tricord server on your network. The IMS managementsoftware can monitor power and cooling status for the main system and anyattached disk-storage cabinets; show status, activity, and firmware revisions ofall installed hardware subsystems (including LED displays, switch settings, andcontrol codes); perform local or remote firmware updates to the IMP, PBS, orBIOS while the system is running; force disk recovery operations;perform extensive statistics analysis of all subsystems; reboot and reconfigurethe system (load drivers, run EISA configuration utilities, and switch to aredundant CPU if available); access the system Event Log; and capture keyboardinput and video output so that all administrator operations from a remoteconsole are run on the server as if you were sitting at the server console.

The IMS will automatically handle as much fault prevention and recovery asit can, post such events to a system log, and notify the administrator whennecessary or directed. The software can generate and send (via pager or SimpleNetwork Management Protocol--SNMP) alerts on administrator-defined events, andfollow rules for what to do in the event of a specific error or hardwarefailure. Hardware-level password security protects the server, so you don't haveto worry about somebody dialing in to your server with the software and messingup your system.

Availability and Fault Tolerance
The Tricord PowerFrame is definitely for enterprise deployment, in bothfunctionality and price. You have to pay for advanced features, but this systemhas plenty of them.

One crucial feature on an enterprise system is uptime. If you're bettingyour entire business on the idea that your server will always be available, ithad better be! Tricord uses redundant controllers (SCSI, network, etc.),redundant power supplies, hot-swap disks, and so on to address this requirementby eliminating as many single points of failure as possible. So far, the companyreports achieving 99.98% server uptime, or less than two hours of downtime in ayear.

The PowerFrame's disk subsystem is fully fault-tolerant, with hot-spares,hot-swaps, duplexed controllers, and many levels of RAID. The memory subsystemcan catch single- and double-bit errors, and correct single-bit errors beforethey cause problems. The server has three 500-watt power supplies. Any powersupply can fail, and you can hot-replace it without affecting the system.Sensors protect the system from heat. They have thresholds that you canconfigure to automatically shut down the server if the sensors detect heatproblems. And, you can configure a multiprocessor system so that if one CPUfails, the server will automatically reboot without it. You will be able to loadbalance and set up fault tolerance with multiple NICs, when NT supports thesecapabilities.

Is Bigger Better?
Although the PowerFrame is an enormous box for a PC server, it is a wellthought-out, modular design: All components are easy to access and replace. Thebox has plenty of room for cards, additional drives, CPU and memory upgrades,and advanced networking options. Windows NT Magazine Lab tests (which Iexplain in, "Optimizing Exchange to Scale on NT.") showed that thehardware handles NT just fine, with CPU and memory scaleability that you expectfrom such a system.

No, this box is not for the meek. But Tricord is for those who haveenterprise applications or heavy user loads to address with one server (toreduce administration hassles); want to consolidate an existing multiserversetup into one; or just want an extremely powerful, robust, and scaleableplatform. Support plans are available in addition to the one-year onsitewarranty you get with the initial purchase, and 24 X 7 technical assistance isalways available over the phone.