zOS learning 02 - z Series/ zOS学习笔记02 - z 系列主机

本节笔记在上节看完ESA/390的基础上学习z 系列主机

一、z Architecture Overview

z系列的架构图：

包括了z Series 800 890 900 和990全系列的产品，数字越大机器越好，也越贵。。。

可以运行z/VM, z/OS, z/OS.e 和Linux(当然是定制的linux)。z/VM是一个操作系统，可以在他上面同时运行复数的操作系统；强调一下，这里的Linux不是运行在虚拟机上的Linux，而是真正运行于z Series 上的linux。关于这部分现在略过，日后用到再看。http://en.wikipedia.org/wiki/Linux_on_System_z

软件是基于z Architecture的。

下面是英文的说明：

“z/Architecture is an extension to S/360, S/370, S/390 and ESA/390 architectures. z/Architecture was announced in late 2000 as the next generation of architecture.

z/Architecture provides a set of definitions and rules required for the interaction of z/Architecture hardware and software.

z/OS and z/OS.e are designed to run on a z/Architecture platform. z/OS.e is a special low priced offering of z/OS which is designed to exploit the fast-growing world of next generation e-business. z/OS.ei s not a different operating system from z/OS, but it lacks some z/OS functionality. From the perspective of an end-user, z/OS and z/OS.e are identical, and both systems are referred to generically as z/OS in this class.

z/Architecture still provides a high degree of compatibility with its ancestors, ESA/390, S/390, S/370, S360”

我们获得以下信息：

1. z/Architecture 由S/360, S/370, S/390 and ESA/390发展而来，包括软件/硬件整套，有继承性，并且和这些旧系统/架构兼容度很高（哪些地方？还不知道，学习中）。

2. z/OS.e 就是z/OS的阉割版（economical）。

二、z Architecture Design

和S/360相比，z Architecture设计更为复杂，大概在2001年成型，主要体现在以下三点：

1. I/O connectivity

IO连接上，和S/360相比，有以下差异（请翻到http://blog.csdn.net/musiccow/article/details/8485528 zOS learning 01 - mainframe/ zOS学习笔记01 - 大型主机）

（1）ESCON and FICON channels

ESCON（Enterprise Systems Connection） FICON（Fibre Connection）都是IBM的数据传输协议；FICON已经达到100km的传输距离，8Gbps的传输速度，正在取代ESCON(136Mbps,43km)，协议内容就不看了，以后用到再看。总之就是IO速度更快传的更远了（损耗下降，抗扰性，纠错性强之类）
（2）Switches to connect peripheral devices to more than one CEC

可以把外设同时接在不同CEC(同CPC，中央处理器复合体central processor complex)上？这一条不太清楚，待学习。

（3）CHPID addresses are two hex digits

CHPID（是channel Path ID吧？）的地址变成了16×16=256个，由两个十六进制数组成，如4A。S/360有16个，用一个十六进制数表示就足够了，比如B。

（4）Multiple partitions can share CHPIDs

对于partition的概念我还不理解，先留个问号？
（5）I/O subsystem layer exists between the operating system and the CHPIDs

在OS和CHPIDs之间有一个叫I/O系统层的东西。什么是I/O subsystem ？这里有篇文章可以参考 http://www.transitmagazine.com/lib0077.html。计算机的同学应该知道设备是需要驱动才能工作，对程序来讲，不同设备的调用函数不同，比如读U盘叫usb_read,读CD叫cd_read,那程序员就记不住了。这样，通过I/O subsystem 将不同设备的I/O函数对应到统一的系统API上，比如create,read,write等函数对设备进行同一的I/O操作，编程就省心了，app只用通过OS调用这些函数就可以操作设备IO了，不需要去留意各种设备的差异。

（6）设备号：

设备地址通过IOCDS（Input/Output Configuration Data Set）转换后成为device number，然后才能用在zOS中.

设备号由3或4个十六进制数构成，就是16×16×16×16=65536个可用地址。

2. Partitioning of the system

CPC可以从逻辑上分割成多个partition，最大的一个特点是可以在一个CPC上同时运行多个系统如zOS，很多人可以在不同的系统上干不同的事，生产、测试，互不相干；

LPAR或者LP（logical partitions）这个概念：

LP从逻辑上看，是CPU/存储器/通道等等资源的集合，这些资源被划归运行在它上面的操作系统，z/OS, OS/390，VM或者是Linux；每个LPAR都可以运行一个OS，和单机运行一个OS的效果是类似的。

注意LPARs和VM的概念不同，LPARs是硬件上通过microprocessor来控制资源的分配（见下图），给每个LPAR划分一部分CPU/内存/Channel资源，一般是system administrator去手动分配，CPU和Channel都可以让某个LP独享或多个LP共享，Storage的共享需要reconfigure。重新划分需要修改

详细请看下面一段英文描述：

“System administrators assign:Memory, Processors, CHPIDs either dedicated or shared. This is done partly in the IOCDS and partly in a system profile on the Support Element (SE) in the CEC. This is normally updated through the HMC. Changing the system profile and IOCDS will usually require a power-on reset (POR) but some changes are dynamic”

“Each LP is a set of physical resources (CPU, storage, and channels) controlled by just one independent image of an operating system,such as z/OS, OS/390, Linux, CFCC, VM or VSE.
Each LP is defined through IOCP/HCD. For example, the IOCP RESOURCE PARTITION= ((LP1,1),(LP2,2)) statement defines two LPs.A Power-on-Reset (POR) operation is required to add or remove LPs.
LP options, such as the number of logical CPs, the LP weight, whether LPAR capping is to be used for this LP, the LP storage size (anddivision between central storage and expanded storage), security, and other LP characteristics are defined in the Activation Profiles on the HMC.
Individual physical CPscan be shared between multiple LPs, or they can be dedicated for use by a single LP.
Channels can be dedicated, reconfigurable (dedicated to one LP, but able to be switched manually between LPs), or shared (if ESCON or FICON).
The processor storage used by an LP is dedicated, but can be reconfigured from one LP to another with prior planning.”

VM的话指z series上安装了zVM，再在zVM上安装多个OS，靠zVM来手动/自动分配资源。也是说可以在LPAR1上安装zVM, 然后再在zVM上安装一个zOS，一个Linux. 资源的分配仅限在LPAR内。

本节完。