Microservers are the latest evolutionary development in server design, continuing the trend for higher density, greater power efficiency and easier manageability previously seen in rack-mount and blade servers.
Microservers pack multiple low-power server nodes on blade-like cartridges into a high-density chassis that provides shared networking, power and cooling. Typical microserver workloads are those that scale optimally by adding multiple low-power nodes — simple web serving, static content delivery, offline or batch analytics and low-end dedicated hosting, for example. Processors that service these highly parallelised 'scale-out' workloads include low-power Intel Atom and ARM-based designs; single-threaded workloads that scale better with increased node performance are also accommodated on some microserver platforms, using higher-power nodes based on Intel Xeon or AMD Opteron processors.
HP's Moonshot System is arguably the best-known microserver platform available today. According to HP, Moonshot servers use 89 percent less energy, 80 percent less space, cost 77 percent less and are 97 percent 'less complex' than traditional servers.
The HP Moonshot 1500 Chassis pictured here accommodates up to 45 server cartridges and two high-density low-power switch modules that provide traffic isolation and can be stacked for increased resilience and simplified domain management.
The Moonshot 1500 Chassis accepts three types of server cartridge.
The Proliant m700 Server Cartridge (left) has four AMD Opteron X2150 APUs (Accelerated Processing Units) combining CPU and integrated GPU, each with a TDP (Thermal Design Power) of 11-22W. The m700 is aimed at hosted desktop infrastructure workloads.
The Proliant Moonshot Server Cartridge (right) uses Intel's 8.5W dual-core Atom S1260, includes direct-attached storage and is aimed at low-end web serving workloads.
The Proliant m300 Server Cartridge (middle) uses the 20W eight-core Atom C2750 SoC (System on a Chip) and is aimed at more demanding web workloads.
Whereas traditional servers use dedicated management, networking, storage, power supply and cooling in a single chassis, the Moonshot 1500 Chassis shares these components. It can support 45 server cartridges per 4.3U chassis, accomodating up to 180 nodes when using the 4-processor Opteron-based m700 cartridges.
Each Moonshot 1500 Chassis includes five dual-rotor hot-plug redundant fans, up to two independently paired network and uplink modules, optionally redundant hot-plug power supplies and interconnect modules, and the Moonshot 1500 Chassis Management Module.
Two switch/uplink module combinations are supported: the 45G Switch Module and 6SFP Uplink Module, with 45 1GbE downlink and 6 10GbE SFP+ uplink ports respectively; and the 180G Switch Module and 4QSFP+ Uplink Module, with 180 1GbE downlink ports and 4 40GbE QSFP+ uplink ports respectively.
AMD's SeaMicro SM15000 family of microservers supports up to 64 eight-core AMD Opteron, 64 quad-core Intel Xeon E3-1265Lv2 (Ivy Bridge) or Xeon E3-1260L (Sandy Bridge), or 256 dual-core Intel Atom N570 processors. The Atom-based configuration, which accommodates four CPUs per computing card, is aimed at typical microserver workloads such as web serving and big data applications, while the Opteron- and Xeon-based CPU modules service more demanding cloud, Java and PHP workloads.
The SM15000 chassis is a 30cm-deep 10U unit that fits into a standard 19-inch server rack. The maximum number of CPU cores supported in an SM15000 chassis is 512 (64 8-core Opteron, or 256 dual-core Atom). The chassis also has eight hot-swappable slots for storage cards, each card supporting up to eight 2.5-inch SAS or SATA drives (HDD or SSD). With 1TB 7,200rpm drives installed, that gives a maximum of 64TB per chassis (although most implementations will use a RAID configuration that reduces this headline figure).
The SM15000 chassis has eight slots for Ethernet uplink cards, each card supporting either eight 1GbE ports or two 10GbE SFP+ ports. These uplink ports connect directly to an end-of-row or core network switch. The computing, storage and Ethernet cards are linked via SeaMicro's low-latency, 1.28Tbps-bandwidth Freedom Fabric, whose Torus architecture provides multiple redundant paths between resources to eliminate points of failure.
The above image shows an SM15000 chassis with four 2x10GbE and two 8x1GbE uplink cards, plus two loopback cards.
Dell was a pioneer in the microserver market, launching the high-density XS-11-VX8 'Fortuna' server with hot-plug modules based on Via's low-power Nano processor back in 2009. Fortuna delivered 12 server modules consuming 20-29W per server in a 2U chassis — an unprecedented power/density combination for the time.
Dell's current microserver platform is the PowerEdge C5220 hot-plug server/C5000 chassis combo, pictured above, which packs 8 or 12 server modules into a 3U chassis. Workloads targeted by the PowerEdge C5220 include hosting cloud infrastructure, web serving and content delivery networks (CDN).
The server modules are mounted on vertical 'sleds' that can house dual- or quad-core Intel Xeon E3-1200 or E3-1200v2 processors. Each sled has 4 DIMM slots for up to 32GB of ECC RAM and can accommodate up to four 2.5-inch or two 3.5-inch SATA/SAS drives.
The PowerEdge C5000 chassis (the 12-sled version is shown here) features dual redundant front-mounted power supplies.
The 12-sled C5000 chassis from the top: apart from the cooling fans, everything is accessible from the front.