Technically, Moonshot is an engineering tour de force of the kind HP was once famous for. It starts with an oddly-sized 4.3U (7.5-inch) chassis with slots for 45 server boards, what HP calls cartridges. Like a blade server, the chassis provides shared power, cooling, interconnect and management. However, unlike typical blade designs the cartridges plug in vertically to a slide-out chassis.
The blade comparisons end there because, as HP's Moonshot white paper points out [PDF], the chassis hosts not one, but three independent backplane networks: an Ethernet switching fabric, storage interconnect and what HP calls a cluster fabric. The shipping Moonshot 1500 system includes two removable Ethernet switch modules, supporting four Gigabit links to each switch, though the first server cartridge only includes two Gigabit Ethernet ports. The storage network supports up to four SAS or SATA links, two of which route to external, shared storage and two of which are used for internal, cartridge-to-cartridge interconnects.
Moonshot's cluster fabric is unique and clearly designed to future-proof the platform, as it's unclear how extensively it's used by the first-generation server boards. According to HP's white paper, it's a two-dimensional topology in which "groups of three server cartridges are connected north-south in independent rings and groups of 15 server cartridges are connected east-west in independent rings." There are four lanes in each direction, providing 16 total, that are configured by the cartridge hardware to use one of a variety of supported protocols including PCIe, Ethernet or SAS. However, this means that in the future, when it's possible to mix different cartridge types, system designers will have to pay close attention to how each chooses to use the cluster fabric and do extensive system integration testing.
Which brings us to the server cartridges. HP is able to pack 45 system boards in such a small space by using low-power Centerton Atom S1260 processors, a server-oriented variant of Intel's play for a slice of the tablet market. Unlike current ARM CPUs, the S1260 is a 64-bit x86 part with two hyperthreaded cores (for four total threads) running at 2 GHz and supporting up to 8 GB of ECC RAM, while sipping a mere 8.5 watts. According to this analysis at Anandtech of early performance data from Intel and HP, "performance is going to be heavily dependent on the nature of the workload, with the S1200 designed for and excelling at heavily threaded, simple tasks, while coming up short in lightly threaded scenarios that need bigger, faster cores."
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Indeed, according to Dave Donatelli, executive vice president and general manager of HP's Enterprise group, that's exactly the workload Moonshot is targeting with this first cartridge: Web hosting, cloud services and scale-out applications in high-performance computing and data visualization. Given the Atom's modest compute resources, Moonshot servers must be dedicated to a single task. There's no virtualization support at this point, although Gerald Kleyn, director, Hyperscale Server Hardware R&D at HP, says as the cartridge portfolio fills out, it does plan to eventually support VMware, KVM and OpenStack.
The real value of Moonshot isn't horsepower, but density, efficiency and cost. HP claims the product uses one-ninth the power and takes an eighth the space at about a quarter the cost of conventional x86 servers. With the shared backplane, integrated management interface, use of HP's iLO remote consoles and support by HP Cluster management software, it's actually feasible to operate a rack stuffed with hundreds of servers, and may be no more complex than a comparable rack of blades.
Next page: HP's Platform Strategy