你为什么不从一个“单一的”小“ Cassandra服务器，你通常用MySQL做它吗？ [英] Why don't you start off with a "single & small" Cassandra server as you usually do it with MySQL?

问题描述

对于刚刚开始的任何网站，负载最初是最小的，最初以缓慢的速度增长。人们通常从他们的基于MySQL的站点开始，使用单个服务器（也是VPS，而不是专用服务器）作为应用服务器以及DB服务器和服务器运行。通常得到太远这个设置&只有当他们感到需要他们从应用程序服务器分离数据库，给它一个单独的VPS服务器。

For any website just starting out, the load initially is minimal & grows with a slow pace initially. People usually start with their MySQL based sites with a single server(***that too a VPS not a dedicated server) running as both app server as well as DB server & usually get too far with this setup & only as they feel the need they separate the DB from the app server giving it a separate VPS server. This is what a start up expects the things to be while planning about resources procurement.

但是到目前为止，我看到的是，Cassandra有很大的不同。人们通常推荐使用至少一个3节点集群，（在专用服务器上）大量的RAM。 4GB或8GB RAM是他们建议开始。所以Cassandra需要比MySQL更多的硬件资源，网站提供类似的性能，服务类似的负载/相同数量的数据。我理解Cassandra的更高的存储要求，因为复制，但其他硬件资源呢？

But so far what I have seen, it's something very different with Cassandra. People usually recommend starting out with atleast a 3 node cluster, (on dedicated servers) with lots & lots of RAM. 4GB or 8GB RAM is what they suggest to start with. So is it that Cassandra requires more hardware resources in comparison to MySQL, for a website to deliver similar performance, serve similar load/ traffic & same amount of data. I understand about higher storage requirements of Cassandra due to replication but what about other hardware resources ?

我们不能像基于Cassandra的应用程序开始，就像MySQL一样。从1或2 VPS&需要时添加更多？

Can't we start off with Cassandra based apps just like MySQL. Starting with 1 or 2 VPS & adding more whenever there's a need ?

我不想比较苹果和橘子。我只是想知道当我开始使用单节点基于VPS的Cassandra安装VS单节点基于VPS的MySQL安装时，我可能会有多么危险的情况。这两种情况的区别。 Cassandra服务器更容易不可用于MySQL服务器？如果我把tomcat和Cassandra一起放在单个服务器上使用LAMP堆栈，那么什么是坏的。

I don't want to compare apples with oranges. I just want to know how much more dangerous situation I may be in when I start out with a single node VPS based cassandra installation Vs a single node VPS based MySQL installation. Difference between these two situations. Are cassandra servers more prone to be unavailable than MySQL servers ? What is bad if I put tomcat too along with Cassandra as people use LAMP stack on single server.

推荐答案

DR;
可以从单个节点开始，但是您可以忽略c *的高度可用因素。

Cassandra是为处理大量数据，千兆字节和在某些情况下petabyte 。许多用户通常从MySQL（和许多其他RDBMS）切换到Cassandra，一旦他们发现他们当前的数据库系统不能有效地处理数据加载（查询变慢，管理存储变得具有挑战性等）。

Cassandra is built for systems that handle huge volumes of data, terabytes and in some cases petabytes. Many users typically switch from MySQL (and lots of other RDBMS) to Cassandra once they find that their current DB system can't handle the data load efficiently (querying gets slow, managing storage becomes challenging etc.)

4-8 GB的RAM是与JVM和ram的大小有效垃圾收集。建议是说，不应该从8 GB开始，但帽子你不应该有超过8GB

The 4-8 GB of ram is to do with the JVM and the size of ram on efficient garbage collection. The advice is stating not that you should start on 8 GB, but hat you shouldn't have more than 8GB

这并不意味着你不能使用Cassandra在非常基本的机器上启动单个节点（有些人实际上有cassandra运行在树莓pi ）。

This doesn't mean to say that you cant use Cassandra to start up a single node on a very basic machine (some people actually have cassandra running on a raspberry pi).

的cassandra的主要卖点。如果你有两个节点 RF = 2，那么如果一个节点出现故障，你就不能执行写操作。如果您有3个节点，您仍然可以执行读取和写入。

Availability is one of cassandra's main selling points. If you have 2 nodes with RF=2 then you cant perform writes if a single node goes down. If you have 3 nodes you can still perform both reads and writes.

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