Official Google Cloud Certified Associate Cloud Engineer Study Guide by Dan Sullivan;

Author:Dan Sullivan; [Sullivan, Dan]
Language: eng
Format: epub
ISBN: 9781119564393
Publisher: John Wiley & Sons, Inc. (trade)
Published: 2019-03-20T16:00:00+00:00

Nanoseconds, Milliseconds and Microseconds

Some storage systems operate at speeds as unfamiliar to us as what happens under an electron microscope. One second is an extremely long time when talking about the time it takes to access data in-memory or on disk. We measure time to access, or “latency,” with three units of measure.

Nanosecond (ns), which is 10-9 second

Microsecond (μs), which is 10-6 second

Millisecond (ms), which is 10-3 second

Note, the number 10-3 is in scientific notation and means 0.001 second. Similarly, 10-6 is the same as 0.000001, and 10-9 is the same as 0.000000001 second.

Another consideration is persistence. How durable is the data stored in a particular system? Caches offer the lowest latency for accessing data, but this type of volatile data exists only as long as power is supplied to memory. Shut down the server and away goes your data. Disk drives have higher durability rates, but they can fail. Redundancy helps here. By making copies of data and storing them on different servers, in different racks, in different zones, and in different regions, you reduce the risk of losing data due to hardware failures.

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