MAINFRAME 硬體架構演化史{1}

本文給給出簡單的zos硬體的演化史，
主要內容包括：CPC,CHANNEL ,STORAGE,CU,DEVICE,TAPE
需要瞭解的是硬體是如何定址的;
如的device X的地址為：132

到了後面為了增加IO的效能，新增了DIRECTOR,SWITCH,作為channel與CU的中間緩衝機制，
需要注意的是DIRECTOR,SWITHCH就是一個資料轉寄裝置，高速的

 

  
An ESCON director or FICON switch is a sophisticated device that can sustain high data rates through many connections. (A large director might have 200 connections, for example, and all of these can be passing data at the same time.) The director or switch must keep track of which CHPID (and partition) initiated which I/O operation so that data and status information is returned to the right place. Multiple I/O requests, from multiple CHPIDs attached to multiple partitions on multiple systems, can be in progress through a single control unit. 
 

同時為了便於管理IO的活動在LPAR與channel之間，增加了一個IO SUBSYSTEM,

 

  
An I/O subsystem layer exists between the operating systems in partitions (or in the basic machine if partitions are not used) and the CHPIDs. 
 

IO subsystem的作用就是完成卷標到物理地址的映射。zos 只認識卷標（device number）

 

  
The I/O control layer uses a control file known as an IOCDS (I/O Control Data Set) that translates physical I/O addresses (composed of CHPID numbers, switch port numbers, control unit addresses, and unit addresses) into device numbers that are used by the operating system software to access devices. 
 

關於UCB :
Modern control units, especially for disks, often have multiple channel (or switch) connections and multiple connections to their devices, as shown in Figure 8. They can handle multiple data transfers at the same time on the multiple channels. Each device will have a unit control block (UCB) in each z/OS image.
注意UCB是os image 層級的概念，這也為HYPAV 提供了可能。
如：
下面給出drive的概念：


這裡需要注意的是：3990CU 與3390 磁碟以及第二幅圖3390的最新實現

 

  
The 2105 unit is a very sophisticated device. It emulates a large number of control units and 3390 disk drives. It contains up to 11 TB of disk space, has up to 32 channel interfaces, 16 GB cache, and 284 MB of non-volatile memory (used for write queueing). The Host Adapters appear as control unit interfaces and can connect up to 32 channels (ESCON or FICON). 
 

The internal processing (to emulate 3990 control units and 3390 disks) is provided by four high-end RISC processors in two processor complexes; each complex can operate the total system. Internal batteries preserve transient data during short power failures. A separate console is used to configure and manage the unit.