Virtualization2.0 简明教程
Preparing the Infrastructure
至少在服务器级别，虚拟化已经使用了很长时间。此后，该概念已扩展到用户、应用程序、网络、安全、存储，当然也扩展到了桌面虚拟化 (VDI)。因此，要在所有这些概念中实施，我们必须事先准备一个基础设施，该基础设施分为一些关键组件。
Virtualization, at least at the server level, has been in use for some time. Since, the concept has expanded to the User, Application, Network, Security, Storage, and of course to Desktop Virtualization (VDI) as well. Therefore, to roll out in all these concepts, we have to prepare an infrastructure before, which is divided in some key components.
第一个是 Hypervisor ，我们在前面的章节中已经讨论过。这项工作需要的一些重要规格包括：处理器、内存和网络模式等。
The First one is Hypervisor and we have discussed it in the earlier chapters. Some important specifications needed for this job are – Processors, Memory and Networking Modes, etc.
Networking - LAN and WAN Optimization
VDI 可能非常占用资源 —— 这包括通过线缆传输的流量。拥有一台好的 core-switching infrastructure 将通过允许管理员创建与流量动向相关的特定规则和策略来帮助减轻这个痛苦。
VDI can be very resource intensive – this includes traffic over the wire. Having a good core-switching infrastructure will help alleviate this pain by allowing the administrators to create certain rules and policies revolving around traffic flow.
为特定于 VDI 的流量设置 QoS metrics 可以帮助消除拥塞，并确保正确的流量拥有适当的优先级。至于离开数据中心的流量，了解用户的位置并根据某些标准优化他们的体验非常重要。
Setting up QoS metrics for VDI-specific traffic can help remove congestion and ensure that the right traffic has the proper amount of priority. As for the traffic that is leaving the data center, knowing where the user is located and optimizing their experience based on certain criteria, becomes very important.
另一个重要方面是存储。大型组织将拥有大量存储控制器。同时，一些较小的组织只会使用一个存储控制器。无论可用的存储控制器数量多少，都需要根据 VDI 为其正确调整大小。
Another significant aspect is storage. Large organizations will have numerous storage controllers. At the same time, some smaller organizations will be using only one. Regardless of the amount of storage controllers available, they need to be sized properly for VDI.
为了防止启动和处理风暴，组织必须查看其映像的 IOPS 要求。为了减轻处理痛苦，管理员可以查看 Flash Technologies ( NetApp, Fusion-IO, XtremIO ) 或 SSD Technologies ( Violin, Nimbus )，以帮助卸载这种类型的负载。此外，Atlantis ILIO 等中介平台运行在虚拟机之上，该虚拟机利用大量 RAM 作为关键存储存储库。
To prevent boot and processing storms, organizations must look at IOPS requirements for their images. To alleviate processing pains, administrators can look at Flash Technologies (NetApp, Fusion-IO, XtremIO) or SSD Technologies (Violin, Nimbus) to help offload that kind of workload. Furthermore, intermediary platforms like Atlantis ILIO run on top of a virtual machine that utilizes massive amounts of RAM as the key storage repository.
Understanding Different File Systems
文件系统根据其功能而有所不同。以下是其中一些最常见的文件系统 -
File systems are varied depending on their functions. Some of the most common ones are listed below −
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Virtual Machine File System- VMFS
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Network File System- NFS
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New Technology File System- NTFS
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Raw Device Mapping- RDM
让我们详细讨论其中的每一个。
Let us discuss each of these in detail.
Virtual Machine File System
VMFS 是 VMware 专有的文件系统。它是一个群集文件系统，可以同时装载到多台服务器上。这有助于每个主机同时连接到任何文件系统，这是 VMware 首选的专有系统所预期的。大多数 VMware 管理程序都可以在其他文件系统上运行，但默认选择和首选选择是 VMFS。
VMFS is a file system proprietary to VMware. It is a clustered file system and it can be mounted on multiple servers simultaneously. This helps every host to connect to the any file system at the same time, which is expected from a proprietary system preferred by VMware. Most of the VMware hypervisors will work with other file systems, but the default choice and the preferred choice is VMFS.
Network File System
NFS 是一个最初由 Sun 开发的系统，但现在是一个开放标准系统。通常在 UNIX 和 Linux 世界中使用。它是一个分布式文件系统。它可以装载到一台服务器上，并且网络将用于向多台计算机共享信息。
NFS is a system that was originally developed by Sun, but is now an Open Standard system. Used commonly in the UNIX and Linux world. It is a distributed file system. It can be mounted on one server and the network will be used to share information to multiple machines.
Choosing Between Different Types of Storage
所有的存储设备都被分成三类，分别是 -
All the storage devices are divided into three categories, which are −
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Direct-Attached Storage
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Network-Attached Storage
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Storage-Area Network
Let us understand each of these in detail.
Direct-Attached Storage
DAS 是你的本地硬盘驱动器。每台计算机都可以有一个或多个本地硬盘驱动器。它主要用于小型虚拟化系统。此解决方案适用于少量来宾计算机。它是存储最便宜和最简单的方法。你还可以使用此方法连接外部硬盘驱动器，将任何来宾计算机加载到该外部硬盘驱动器，这是一个快速简单的启动方法。
DAS is your local hard drive. We can have one or more local hard drives in every machine. It is mostly used for small-virtualized systems. This solution is appropriate for a small amount of guest machines. It is the cheapest and the easiest method of storage. You can connect an external hard drive too with this method, load any guest machines onto that external hard drive, and that is just a quick and easy way to get rolling.
例如 - 一台在上面有本地硬盘的服务器。该类型的管理程序可以容纳不超过 10-20 台虚拟机。示例设备可以是带有八个本地硬盘的 HP 服务器，如下面的插图所示。
For example – A server that has local hard discs on it. That type of hypervisor can hold not more that 10-20 VM machines. A sample device can be a HP Server with eight local hard discs as shown in the following illustration.
Network-attached Storage
NAS 是“在网络上与他人共享其自己存储并且以最简单的形式充当文件服务器的任何服务器”。网络附属存储通过网络共享文件。使用的一些最重要的协议是 SMB, NFS, CIFS, 和 TCP/IP 。当你在 Windows 系统的文件服务器上访问文件时，它就是 NAS
NAS is "Any server that shares its own storage with others on the network and acts as a file server in the simplest form". Network Attached Storage shares files over the network. Some of the most significant protocols used are SMB, NFS, CIFS, and TCP/IP. When you access files on a file server on your windows system, it is NAS
NAS 将使用以太网连接来通过网络共享文件。NAS 设备将有一个 IP 地址，然后可以通过该 IP 地址通过网络访问。NAS 的最大提供商是 QNAP 和 Lenovo 。
NAS will be using an Ethernet connection for sharing files over the network. The NAS device will have an IP address and then will be accessible over the network through that IP address. Biggest providers of NAS are QNAP and Lenovo.
下图显示了 NAS 的工作原理。
The following illustration shows how NAS works.
Storage-area Network
SAN 允许多台服务器共享存储池；使其对服务器看起来像是本地存储或直接附加存储。专用网络标准 Fibre Channel 已被开发出来，以便允许块在服务器和存储之间高速移动。它使用专用交换机和基于光纤的布线系统，将其与遍历繁忙企业网络的日常流量分开。而成熟的 SCSI 协议使服务器的主机总线适配器和磁盘系统之间的通信成为可能。
SANs allow multiple servers to share a pool of storage; making it appear to the server as if it were local or directly attached storage. A dedicated networking standard, Fibre Channel, has been developed to allow blocks to be moved between servers and storage at high speed. It uses dedicated switches and a fiber-based cabling system, which separates it from the day-to-day traffic traversing the busy enterprise network. While the well-established SCSI protocol enables communication between the servers’ host bus adaptors and the disk system.
下图显示了 SAN 交换机如何运行。
The following illustration shows how a SAN switch operates.
