Dell's newest is a chip off the old blade

Second-generation PowerEdge 1855 blade system excels at networking options

Blade servers are evolving at a feverish pace, and Dell’s PowerEdge 1855 system shows just how far the technology has come.

Previous blade systems I’ve seen suffered from severe restrictions and trade-offs, mainly in regard to expandability, connectivity, and ease of use. Dell does a respectable job addressing those trade-offs in its second-generation blade platform -- particularly network communications.

Disappointing density

The Xeon-driven PowerEdge 1855 -- which replaces the Pentium III-based PowerEdge 1655MC -- is similar to other modern blades. It has a 7U chassis designed to fit into a standard rack. You can slide as many as 10 dual-processor servers into the front of each chassis.

In the back are field-replaceable power supplies, fans, and networking connections. The blades and the network infrastructure are linked by a passive midplane that generally doesn’t require servicing. A KVM switch and a management processor are also built into each chassis.

A key consideration for many blade systems is density, and here Dell comes up short. The PowerEdge 1855 system handles as many as six chassis, or 60 servers, in a standard 42U-high rack. This density is noticeably lower than with other dual-processor systems: RLX’s 600ex system handles 70 servers per rack, IBM’s BladeCenter 84 servers, and Hewlett-Packard’s BL20p system 96 servers.

Along with their higher densities, several manufacturers (including HP and IBM) offer the option of installing double-width quad-processor blades. Dell doesn’t, and according to the product manager, the PowerEdge 1855 platform won’t support that option in the future.

Processor choice is also disappointing: Dell offers only Intel Xeon chip processors in the PowerEdge 1855. Other vendors offer more -- for example, HP offers Xeon and AMD Opteron processors in its systems; IBM can mix-and-match Power and Xeon; Sun offers Xeon, Opteron, and UltraSparc chips.

Where Dell does offer more choice is in the back of the chassis. There are four bays for hot-swap power supplies, and each bay has integrated fans and two separate cooling modules. There are also four bays for communications modules, two of which are dedicated to a group of five servers. Each server group uses one communications bay for a Gigabit Ethernet pass-through or switch. The second bay is for optional daughter cards installed into the server, and can have either switches or pass-throughs.

There’s also a removable management module that contains the KVM switch’s connectors and an Ethernet management jack. The management module can be deployed in a redundant pair. However, the communications modules can’t be made redundant, short of duplicating connections via the daughter cards.

The system I tested had only three servers installed, each of which had an FC (Fibre Channel) daughter card. The second communications bay had an FC pass-through (you can also place a second Gigabit Ethernet switch in that bay). According to Dell, a Brocade FC switch and InfiniBand pass-through will ship in March.

The server blades are well-designed. Each of the three I received contained dual 3.6GHz Xeon processors, 1GB RAM (expandable to 12GB, or 16GB with higher-density DIMMs), one onboard Gigabit Ethernet interface, and dual 73GB Ultra320 SCSI hard drives. All three servers were running Windows Server 2003, but Dell supports several Linux distributions.

The drives are hot-swappable, and there’s an onboard RAID controller that ties them together into a mirrored configuration. I’d like to see a less-expensive SATA option, but according to a Dell product manager, there has been little customer demand for non-SCSI drives.

Fast I/O expandability is the PowerEdge 1855’s best design feature. The two daughter card connectors inside each blade can be populated by PCI-X or PCI Express cards. Dell preinstalled a QLogic FC host-bus adapter in one bay of the review system; Gigabit Ethernet is also available, and InfiniBand will ship in March, according to Dell. There’s also a management processor chip on each blade, accessible via the LAN.

Each blade has two small buttons on its front, one for power and one for switching the KVM system. Unlike many other high-end blade systems, there’s no shared CD-ROM or DVD-ROM drive in the chassis. To install software locally, instead of from a network drive, you must plug the external optical drive into a strange video/USB connector on the blade’s front. It’s a clumsy arrangement, but adequate for most blade server installations.

Must-have management

Management is one of the important features of a blade system. That’s why smaller companies such as RLX, with its superior Control Tower software, can compete against behemoths such as Dell, HP, and IBM.

However, the PowerEdge 1855 includes only basic browser-based, Web-based tools for monitoring the blade servers. Dell’s reviews team shipped me a separate PowerEdge 2650 (a 2U conventional server) with OpenManage IT Assistant, its remote management suite. Unfortunately, you can’t see much indication of system status or faults when you’re looking at the blade chassis and servers, so you have to turn to management software for that data.

OpenManage is similar to HP’s Insight Manager and is adequate for checking basic hardware status and generating fault alerts. It’s intuitive and easy to use, but it doesn’t extend down into the software of a blade system. That means it can’t, for example, automate server-image provisioning, manage fail-over, or even monitor application health. Therefore, Dell resells Altiris’ Management Suite for Dell Servers, which includes tools for building remote servers, creating and deploying server images, monitoring hardware and software, updating the BIOS, and managing patches.

Dell included a copy of Altiris in my review system, and it’s a definite improvement on OpenManage. Altiris costs $799 for a 10-pack license, but it’s money well spent; I recommend that anyone installing more than a handful of blades use Altiris Management Suite.

Overall, the PowerEdge 1855 blade system is a tremendous improvement on the first-generation PowerEdge 1655MC system, and it competes well with other dual-processor Xeon systems. The range of communications options, thanks to the two fast I/O daughter cards in each server, is impressive. However, that’s tempered by the lower rack density and by the limited processor choices.

If you can handle the lower density and don’t mind using third-party management software, Dell’s system is a strong contender for your next enterprise blade platform.

InfoWorld Scorecard
Management (15.0%)
Scalability (20.0%)
Availability (25.0%)
Value (10.0%)
Serviceability (10.0%)
Performance (20.0%)
Overall Score (100%)
Dell PowerEdge 1855 7.0 8.0 9.0 8.0 8.0 8.0 8.1
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