In this section, we will take a look at the chips and boards commonly used in various enterprise computer systems.

RAID cards refers to a SAS or SATA controller with RAID function, such as LSI 9560 8i. HBA cards refers to a SAS or SATA controller without RAID function, such as: sas 9300 16i,the controller can be directly welded to the mainboard and connected to the CPU through the PCIE bus. You can also make a PCIE card and insert it into a PCIE slot on the mainboard. PCIE cards come in many forms.

One is standard (full-height full-length, half-height half-length, etc. At present, they are basically half-height and half-length), and the other is non-standard or customized (these cards are in various forms, but still use the PCIE protocol, but the physical interface form changes). One type of non-standard Card, called a Mezzanine Card, is designed to save space in the computer case by having slots that are vertically oriented rather than parallel to the surface of the board, so that the card sits parallel to the motherboard.

The hard disk of an enterprise computer is plugged into a backplane and wired to the SAS HBA/RAID controller. Sometimes you need to connect more hard disks, and the number of direct connection ports of the SAS controller is not enough, so you need to use a SAS Switch (the industry is not called Switch, but SAS Expander) chip to expand the number of interfaces.

This chip can be placed on the backplane, and the hard drive signal is first connected to the SAS Expander, and then connected to the SAS controller from its uplink port. If the backplane space is relatively small, can not accommodate the SAS Expander chip location, in order to consider flexibility, Microsemi company introduced SAS Expander card, which is a PCIE card, but only use the PCIE interface to power, do not transmit signals. The SAS interface is exported from the SAS Expander to the connector.

In this way, the upstream signals of the backplane and SAS controller are connected to the SAS Expander card using cables. In this way, a SAS switching network is formed, and the SAS controller can identify all hard disks.

There is another chip often used in some enterprise computers: the PCIE Switch. As the number of PCIE channels provided by the CPU is not enough, just like SAS, a Switch chip is needed to expand the number of PCIE channels. Enterprise computer systems also contain some chips, such as BMC, sound processing chip/card, GPU/ graphics card, mechanical hard disk controller chip, solid state disk controller chip and so on.