参考：https://www.doit.com.cn/p/author/xigua
参考：http://www.doit.com.cn/p/196056.html
图片说明：
IBM XIV存储系统采用标准的IBM T42机架交付，完全连接15台节点。
满配XIV由15个节点组成，包含6个Interface Node（Interface Module）+ 9个Interface Node（Interface Module）。每一个节点都是一台针对数据存储优化的英特尔X86服务器，并且都有12块SATA盘。
To convey the concepts that the XIV Storage System architecture is based on, it is useful to first look at the physical design.The XIV configuration includes data modules, interface modules, interconnect switches, and uninterruptible power supply (UPS) units.
Modules
The primary components of the XIV Storage System are known as modules. Modules provide processing, cache (including optional flash cache), and host interfaces. They are composed of “off the shelf” systems that are based on Intel technology.The modules are redundantly connected to one another through an internal switched network.All of the modules work together, concurrently, as elements of a grid architecture. This helps the system harness the parallelism that is inherent in such a distributed computing environment.
Important: Flash cache is an optional feature. However, if you opt for the flash cache extension, flash cache devices must be installed in all modules
Data modules
At a conceptual level, data modules function as the elementary building blocks of the system.They provide storage capacity, processing power, and caching functions in addition to advanced system-managed services. The data modules’ abilities to share and manage system software and services are key elements of the physical architecture
Interface modules
Interface modules are equivalent to data modules in all aspects, with the following exceptions:
In addition to disk, cache, and processing resources, interface modules include both Fibre Channel and IP network Small Computer System Interface (iSCSI) interfaces for host system connectivity, remote mirroring, and data migration activities. the picture above conceptually illustrates the placement of interface modules within the topology of the XIV Storage System architecture. The system services and software functions associated with managing external I/O is located exclusively on the interface modules.
Module interconnect switches
The XIV Storage System contains a redundant switched network, based on InfiniBand, that transmits both data and metadata traffic between the modules. Traffic can flow between two interface modules, between two data modules, and between an interface module and a data module.
