What are DASD volumes and labels?

DASD volumes are used for storing data and executable programs (including the operating system itself), and for temporary working storage. DASD labels identify DASD volumes and the data sets they contain.

 

DASD 卷被用于数据的存储数据和可执行程序（包括操作系统自己），也可以作为临时的工作存储器使用。

他们包括DASD的标签的定义DASD卷和数据

 

One DASD volume can be used for many different data sets, and space on it can be reallocated and reused. On a volume, the name of a data set must be unique. A data set can be located by device type, volume serial number, and data set name. This structure is unlike the file tree of a UNIX® system. The basic z/OS® file structure is not hierarchical. z/OS data sets have no equivalent to a path name.

 

一个DASD 卷可以用于不同的数据设置和创新分配空间在使用。在一个卷上，数据的名字必须设置成惟一的。一个数据被指定成：

设备类型，卷的序号和数据的名字。这个结构不像 unix 的文件树。 基本的文件不分级。 数据设置没有相当的路径名

 

Although DASD volumes differ in physical appearance, capacity, and speed, they are similar in data recording, data checking, data format, and programming. The recording surface of each volume is divided into many concentric tracks. The number of tracks and their capacity vary with the device. Each device has an access mechanism that contains read/write heads to transfer data as the recording surface rotates past them.

 

虽然 DASD 卷不同于物理的表面，体积和速度， 但是，他们都能进行数据记录，数据检测，数据格式化和编程。每个卷的记录被分成

一个同轴的路径。路径的号码和体积随设备变化。每个设备有一个访问点，它们包含读取和写入的头去转换这些数据来作为记录这些流过的数据。

 

The operating system uses groups of labels to identify DASD volumes and the data sets they contain. Customer application programs generally do not use these labels directly. DASD volumes must use standard labels. Standard labels include a volume label, a data set label for each data set, and optional user labels. A volume label, stored at track 0 of cylinder 0, identifies each DASD volume.

 

The z/OS system programmer or storage administrator uses the ICKDSF utility program to initialize each DASD volume before it is used on the system. ICKDSF generates the volume label and builds the volume table of contents (VTOC), a structure that contains the data set labels. The system programmer can also use ICKDSF to scan a volume to ensure that it is usable and to reformat all the tracks.