dasd

Years ago in I / T the cost and space of DASD was a more important consideration .

数年前，在I/T中DASD的成本和空间是更重要的考虑因素。

Typically , users will store objects into DASD initially .

典型情况下，用户最初会将对象存储在DASD中。

A user , group , or DASD data set that is defined to RACF .

在资源存取控制软件（RACF）中定义的一个用户、一组用户或者磁盘（DASD）数据集。

Such designs not only waste DASD space , but also require higher resource consumption for many DB2 operations .

这种设计不仅浪费DASD空间，而且，对于很多DB2操作，还需要消耗更多的资源。

We distributed the DASD for the user mail boxes over these mount points .

我们将用于用户邮件箱的DASD分布在这些挂载点上。

The more often that the data requested by applications is in memory rather than out on DASD , the better overall performance will be .

应用程序所请求的数据出现在内存中（而不是外面的DASD上）的概率越大，总体性能就越好。

A storage group is a set of volumes on a physical storage device , DASD ( direct access storage devices ) on the mainframe .

存储组是大型机上物理存储设备DASD（直接访问存储设备）上的一组卷。

Also , we added four more CPs , increased the memory to26 GB , and added more DASD to support the full user load .

而且，我们又增加了4个CP，将内存增加到26GB，并增加更多DASD，以支持全部用户负载。

Let 's simulate this scenario , assuming that objects stay six months in DASD , three years in external storage , and seven years in tapes .

让我们来模拟一下这个场景，假设对象在DASD中存储6个月，在外部存储中存储3年，在磁带中存储7年。

The classical concurrent mode volume groups ( VGs ) only supported Serial DASD and SSA disks in conjunction with the32-bit kernel .

经典并发模式卷组（VolumnGroup，VG）仅支持串行DASD和SSA磁盘以及32位内核。

Place the partitions for the table space and indexes on separate DASD volumes and ( if possible ) separate control units in order to minimize I / O contention .

将用于表空间和索引的分区放在单独的DASD卷中，并且，如果可能的话，要隔开控制单元，以减少I/O争用。

However , over-allocating free space may result in wasted DASD space , less data transferred per I / O , less efficient use of buffer pools and more pages to scan .

然而，过多地分配空余空间可能会产生浪费的DASD空间，导致每次I/O只能传输更少的数据，缓冲池的利用效率更低，并且要扫描更多的页。

This instructs DB2 to pass the index keys to the sort program in memory , rather than having the keys written to and read once again from sort work files on DASD .

这将指示DB2将索引键传递给内存中的排序程序，而不是再次将这些键写到DASD上的排序工作文件中，然后从中读取这些键。

On System z , it takes considerable time for the image to come up since there are many devices ( DASD , network devices , etc. ) attached to the machines that are required to load different images .

在Systemz上，映像启动比较慢，由于机器附加有许多的设备（比如DASD和网络设备等），所以必须加载多个不同的映像。

After being read in from DASD , the data and index pages go into these slots and remain there until the DB2 buffer manager determines that those slots should be used for some other data .

数据和索引页被从DASD中读出之后，便进入这些插槽，并留在其中，直到DB2缓冲区管理器确定那些插槽要用于其他数据。

The advantage of using ECKD DASD devices is that they are visible from the z / VM CMS environment and thus can be easily managed from a typical z / VM system programming environment .

使用ECKDDASD设备的优点是，它们在z/VMCMS环境中是可见的，因此可以从典型的z/VM系统编程环境中轻松地管理它们。

The disadvantage is that the System z I / O architecture specifies that only one I / O operation can be active at any time on a specific target device ( UCB or DASD subchannel ) .

缺点是，SystemzI/O架构规定，一个特定的目标设备（UCB或DASD子通道）上每次只能有一个活动的I/O操作。

This is accomplished by increasing VPSIZE as long as the number of DASD I / Os keeps decreasing until the cost of paging outweighs the benefit of the reduced I / O.

为实现这一点，要使DASDI/O的数量持续下降，并不断增加VPSIZE，直到换页的成本超出了通过减少I/O所带来的好处为止。

In a sense ," DASD is cheap ," and bandwidth is also getting cheaper (" DASD " is an old IBM way of saying " hard disks "; and the phrase is a design cliche ) .

在某种意义上，“DASD很廉价”，带宽也变得越来越廉价（“DASD”是IBM对“硬盘”的旧称；这个措词在设计上很陈腐）。