On a Symmetrix array, this is the time it takes to transfer data from a physical HDD to the Symmetrix cache.
在一个Symmetrix阵列中，这指的是将数据从一个物理hdd传输到Symmetrix所需要的时间。
If the data requested is not in global cache, it must be retrieved from disk and placed into cache before the Symmetrix will respond to the request.
如果所请求的数据不在全局缓存中，那么它必须先从磁盘读取，然后再放进缓存中，之后Symmetrix才会将响应返回给请求。
IBM recommends using intelligent storage servers, such as the IBM ESS or EMC Symmetrix, to establish near-instantaneous copies of the data entirely within itself.
IBM建议使用智能存储服务器，例如IBMess或emcSymmetrix，完全在其内部建立数据的准瞬时拷贝。
In fact, in a Symmetrix storage array, one EFD can deliver IOPS equivalent to thirty 15,000 RPM hard disk drives with a response time of approximately 1 millisecond.
事实上，在一个Symmetrix存储阵列中，一个EFD能够以大约1毫秒的响应时间实现与30个15,000r PM硬盘驱动器相同的IOPS。
Because workloads with high Symmetrix cache read-hit rates are serviced at memory access speed, storing the data needed on EFDs may not result in a significant increase in performance.
因为具有高symmetrix缓存读中率的工作负载都是以内存访问速度实现的，所以在EFD中存储所需要的数据可能不会对性能有大的改进。
Because workloads with high Symmetrix cache read-hit rates are serviced at memory access speed, storing the data needed on EFDs may not result in a significant increase in performance.
因为具有高symmetrix缓存读中率的工作负载都是以内存访问速度实现的，所以在EFD中存储所需要的数据可能不会对性能有大的改进。
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