寻道时间

因此，寻道时间一直是HDD的延迟时间的最主要来源。

Therefore , seek time continues to be the largest source of latency in HDDs .

针对如何提高磁盘调度效率的问题，提出了一种基于平均寻道时间（AST）的磁盘调度优化算法。

To improve the efficiency of disk scheduling , this paper proposed an optimization algorithm of disk scheduling based on the Average Seek Time ( AST ) .

这是因为HDD的性能受到诸如磁头移动（寻道时间）和旋转等待时间等机械约束的限制。

The reason is that HDD performance is limited by mechanical constraints such as head movement ( seek time ) and rotational latency .

数据传输时间一般几毫秒，所以旋转延迟时间和寻道时间是一个物理HDD的主要磁盘延迟时间来源。

Data transfer times are typically fractions of a millisecond , so rotational latency and seek time are the primary sources of disk latency on a physical HDD .

因为EFD没有移动的部件，所以它们不会像FC和SATAHDD那样受到寻道时间或旋转延迟时间的约束。

Because EFDs have no moving parts , they are not constrained by seek time or rotational latency in the way that FC and SATA HDDs are .

WDS25硬盘与发烧级别的VelociRaptor产品有几分类似，不过前者的读写速度更快，其读取/写入寻道时间分别只有3.6ms和4.2ms。

Superficially , the WD S25 appears similarly to the VelociRaptor , but it has much faster read and write seek times at3.6 ms and4.2 ms respectively .

一种基于平均寻道时间的磁盘调度优化算法

Optimization algorithm of disk scheduling based on average seek time

模拟试验表明，磁道预留技术能减少30%以上的寻道时间。

The simulation shows that it can decrease over 30 % seeking .

内部边缘通常具有最短的寻道时间。

The inner edge usually has the slowest seek times .

寻道时间平均值一般为几毫秒，并且它取决于驱动器类型。

Seek time typically averages a few milliseconds and is dependent upon the drive type .

磁盘调度算法，有最短寻道时间优先调度算法和扫描算法。

Disk scheduling , priority scheduling algorithm with the shortest seek time and scanning algorithms .

应该寻找比较长的寻道时间，因为它们会导致应用程序性能降低。

Look for long seek times , as they can result in decreased application performance .

其读写系统使用了飞行式光纤光学头，极大程度地降低了平均寻道时间。

By the use of the fiber optical head , the average access time of the storage system is decreased effectively .

本文还讨论了在该调度算法下，系统的平均寻道时间与I／O请求到达率之间的关系。

This paper also discusses the relationship between the seek time and the I / O ar - rival frequency () .

一般的规则是，靠近中央的数据要比靠近外边缘的数据具有更快的寻道时间。

As a general rule , data that is written toward its center has faster seek times than data written on the outer edge .

当应用程序发出磁盘请求的速率快于磁盘返回数据的速率时，操作系统会让磁盘请求排队，还可能调整请求的次序以降低寻道时间。

The operating system queues disk requests when the applications issue them faster than the disks can return the data , optionally reordering them to minimize seeking .

如果有多个磁盘，那么把负载分配到不同的磁盘上是加快读写速度的有效方法，因为磁盘延迟的最大组成部分是寻道时间。

If you have several disks , splitting load onto separate spindles is an effective way of making reads and writes faster because the largest component of disk latency is the seek time .

而完成一次I/O请求（称为磁盘延迟时间）所需要的时间是寻道时间、旋转延迟时间和磁盘传输时间之和。

The time it takes to complete an I / O request ( referred to as disk latency ) is a combination of seek time , rotational latency , and disk transfer time .

磁盘容量以每年60%速度增长，而磁盘的性能指标，如寻道时间和旋转延迟等仅仅以10%左右的速度增长。

Disk capacity in-creases at the rate of 60 % per year , while the performance parameters of disks , such as seek time and rotational delays , increase at the rate of about only 10 % .

该方法利用光纤光学头的耦合物镜实现对光斑的自动近场聚焦，可实现海量信息的并行读写，并能极大地减少三维存储的寻道时间。

The coupling object lens of optical fiber head can auto-focus the optical spot in near field , so that enormous information can be written and read simultaneously , and the tracking time of three-dimension information storage can be reduced greatly .