Summary

  • 4 minutes
  • Servers mount into racks, come in incremental heights called rack units (for example, 1U, 2U, 3U), and have various depths. Larger cases allow for more expansion and/or redundant components.
  • Servers support more CPU sockets and DIMM slots than a desktop or laptop.
  • There are many types of PCI express cards available to expand servers, including RAID controllers, network cards (1, 10, or 40 gigabit Ethernet), InfiniBand HCAs, storage HBAs, and coprocessors/accelerators, such as GPUs.
  • HDDs and SSDs can attach to a host through SATA or SAS and are used as building blocks for larger storage arrays, often employing RAID technology. These arrays can be a directly attached DAS, a remote block device SAN (using FC or iSCSI), or a remote file server NAS (using CIFS or NFS). Distributed file systems use many servers or arrays in parallel to increase performance and resiliency.
  • Datacenter networking topology is often multitier, with the lowest-tier switches in the same rack (top of rack) or in the same row (end of row).
  • Ethernet remains the de facto standard for datacenter networks, is available at a variety of speeds, and works over copper or fiber-optic cables.
  • InfiniBand is a high-speed interconnect, now popular with HPC, and gaining acceptance in enterprise IT datacenters.
  • Datacenters and server rooms contain racks, raised floors, and cable trays, and are designed with strong physical security.
  • Power distribution comes from the utility company or a backup generator and typically goes through a UPS, through PDUs, to the rack, and then to the server level. Some systems improve efficiency by converting AC to DC fewer times and/or decentralizing the UPS.
  • Servers are most often cooled through CRACs, which push cold air under a raised floor while taking in hot air and removing the heat through a chilled water loop. That loop is attached to a chiller, which itself removes heat by venting through the air or a secondary loop to a cooling tower. Higher densities/efficiencies can be achieved using in-row cooling with hot-aisle containment. Evaporative cooling is also becoming popular for datacenters.
  • Safety is important for both equipment and personnel. FM-200 provides fast, safe fire suppression. All metal surfaces should be properly grounded, and safety equipment should be used appropriately.