en to zh translation catalogue (17 entries)

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en: Measuring block device performance
zh: 测量块设备性能

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en: Measuring throughput
zh: 测量吞吐量

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en: When measuring the impact of using DRBD on a system's I/O throughput, the _absolute_ throughput the system is capable of is of little relevance. What is much more interesting is the _relative_ impact DRBD has on I/O performance. Thus it is always necessary to measure I/O throughput both with and without DRBD.
zh: 当测量使用DRBD对系统I/O吞吐量的影响时，系统所能达到的绝对吞吐量几乎没有相关性。更有趣的是DRBD对I/O性能的相对影响。因此，无论有无DRBD，总是有必要测量I/O吞吐量。

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en: The tests described in this section are intrusive; they overwrite data and bring DRBD devices out of sync. It is thus vital that you perform them only on scratch volumes which can be discarded after testing has completed.
zh: 本节中描述的测试是侵入性的；它们覆盖数据并使DRBD设备失去同步。因此，只在测试完成后可以丢弃的暂存卷上执行它们是非常重要的。

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en: I/O throughput estimation works by writing significantly large chunks of data to a block device, and measuring the amount of time the system took to complete the write operation. This can be easily done using a fairly ubiquitous utility, `dd`, whose reasonably recent versions include a built-in throughput estimation.
zh: I/O吞吐量估计的工作原理是将大量数据写入块设备，并测量系统完成写入操作所需的时间。这可以使用相当普遍的实用程序 `dd` 轻松完成，该实用程序的最新版本包括内置的吞吐量估计。

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en: A simple ``dd``-based throughput benchmark, assuming you have a scratch resource named `test`, which is currently connected and in the secondary role on both nodes, is one like the following:
zh: 一个简单的基于 `dd` 的吞吐量基准，假设您有一个名为 `test` 的临时资源，该资源当前已连接并且在两个节点上都处于次要角色，如下所示：

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en: This test simply writes 512MiB of data to your DRBD device, and then to its backing device for comparison. Both tests are repeated 5 times each to allow for some statistical averaging. The relevant result is the throughput measurements generated by `dd`.
zh: 此测试只需将512MiB的数据写入DRBD设备，然后写入其备份设备进行比较。这两项测试各重复5次，以便进行一些统计平均。相关结果是由 `dd` 生成的吞吐量测量。

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en: For freshly enabled DRBD devices, it is normal to see slightly reduced performance on the first `dd` run. This is due to the Activity Log being "cold", and is no cause for concern.
zh: 对于刚刚启用的DRBD设备，在第一次 `dd` 运行时性能会略有下降是正常的。这是因为活动日志是 `冷` 的，不需要担心。

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en: See our <<ch-throughput>> chapter for some performance numbers.
zh: 有关一些性能数据，请参阅我们的 <<ch-throughput>> 一章。

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en: Measuring latency
zh: 测量延迟

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en: Latency measurements have objectives completely different from throughput benchmarks: in I/O latency tests, one writes a very small chunk of data (ideally the smallest chunk of data that the system can deal with), and observes the time it takes to complete that write. The process is usually repeated several times to account for normal statistical fluctuations.
zh: 延迟测量的目标与吞吐量基准完全不同：在I/O延迟测试中，一个人会写入非常小的数据块（理想情况下是系统可以处理的最小数据块），并观察完成该写入所需的时间。这个过程通常重复几次，以解释正常的统计波动。

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en: Just as throughput measurements, I/O latency measurements may be performed using the ubiquitous `dd` utility, albeit with different settings and an entirely different focus of observation.
zh: 与吞吐量测量一样，可以使用无处不在的 `dd` 实用程序执行I/O延迟测量，尽管设置不同，观察的焦点完全不同。

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en: Provided below is a simple ``dd``-based latency micro-benchmark, assuming you have a scratch resource named `test` which is currently connected and in the secondary role on both nodes:
zh: 下面提供了一个简单的基于 `dd` 的延迟微基准测试，假设您有一个名为 `test` 的临时资源，该资源当前已连接，并且在两个节点上都处于次要角色：

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en: This test writes 1,000 chunks with 4kiB each to your DRBD device, and then to its backing device for comparison. 4096 bytes is the smallest block size that a Linux system (on all architectures except s390), modern hard disks, and SSDs, are expected to handle.
zh: 这个测试用4kiB分别将1000个数据块写入DRBD设备，然后写入其备份设备进行比较。4096字节是Linux系统（除了s390以外的所有体系结构）、现代硬盘和固态硬盘预计要处理的最小块大小。

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en: It is important to understand that throughput measurements generated by `dd` are completely irrelevant for this test; what is important is the _time_ elapsed during the completion of said 1,000 writes. Dividing this time by 1,000 gives the average latency of a single block write.
zh: 重要的是要了解由 `dd` 生成的吞吐量测量与此测试完全无关；重要的是在完成所述1000次写入过程中经过的时间。将此时间除以1000可得出单个块写入的平均延迟。

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en: This is the _worst-case_, in that it is single-threaded and does one write strictly after the one before, i.e. runs with an I/O-depth of 1. Please take a look at <<s-latency-iops>>.
zh: 这是最坏的情况，因为它是单线程的，并且在之前的一个之后严格执行一个写操作，即I/O深度为1的运行。请查看<<s-latency-iops>>。

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en: Furthermore, see our <<ch-latency>> chapter for some typical performance values.
zh: 此外，有关一些典型的性能值，请参阅我们的<<ch-latency>>一章。
