不过，这种紧密的复制有很高的性能成本，并且难于实现，当群集接近某一规模时，还会有伸缩性的问题。
However, such tight replication has a considerable performance cost and implementation complexity, and may also have scalability problems as the cluster approaches a certain size.
原因有很多，但我相信最重要的两个原因是成本和可伸缩性。
There are many reasons, but two that I believe are most important are cost and scalability.
此选项将意味着对解决方案的整体可伸缩性有严重的限制。
This option implies serious limitations on the overall scalability of the solution.
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