DatastaxEnteprise：节点与实例，正确的AMI映像，为什么需要存储 [英] DatastaxEnteprise: node vs instance, correct AMI image, why do I need storage
问题描述
目前，我们正在评估Datastax企业作为Cassandra和Spark的提供者。我们考虑在AWS上部署Datastax集群。
Currently, we are evaluating datastax enteprise as our provider of Cassandra and Spark.We consider deploying Datastax cluster on AWS.
我有以下问题：
1）在 EC2上的Datastax 安装手册的第1步中，我需要选择正确的AMI映像：目前有7个。这是正确的一个：
（DataStax自动聚类AMI 2.5.1-pv，DataStax自动聚类AMI 2.6.3-1204-pv，DataStax自动聚类AMI 2.6.3-1404-pv ... 。）
1) In step 1 of Datastax on EC2 installation manual, I need to choose correct AMI Image: Currently there are 7 of them. Which is the correct one: (DataStax Auto-Clustering AMI 2.5.1-pv, DataStax Auto-Clustering AMI 2.6.3-1204-pv, DataStax Auto-Clustering AMI 2.6.3-1404-pv....)
2）在启动集群的那一刻，我们是否仅为AWS实例或Datastax Enterprise许可费付费？我知道有30天的企业免费试用版，但是在安装过程中，我没有看到可以要求免费试用的步骤？是否有一些在线计算器可用于每月计算集群成本（基于我们创建的实例类型）
2) The moment we launch the cluster, do we pay only for aws instances or also Datastax Enterprise licensing fee? I know there is a 30 days enterprise free trial, but nowhere in the installation process I saw a step where we can ask for the free trial? Is there some online calculator that we can use to calculate the cost of a cluster on a monthy basis (based on the instance types we create)
3）在步骤3中安装过程配置实例详细信息中，我对术语 instance 和 nodes 感到困惑。它们之间有什么区别？如果选择以下选项，会发生什么情况？
3) In the step 3 of the installation process Configure Instance Details, I am confused with terms instance and nodes. What is the difference between them? What happens if I choose:
a）1个实例，--totalnodes 3（在 user data 中）
a) 1 instance, --totalnodes 3 (in the user data)
b）3个实例--tatalnodes 3
b) 3 instance, --tatalnodes 3
c）1个实例---totalnodes 0 --analyticsnodes 3
c) 1 instance, --totalnodes 0 --analyticsnodes 3
d）3个实例---totalnodes 0 --analyticsnodes 3
d) 3 instance, --totalnodes 0 --analyticsnodes 3
4）我们对用例感兴趣，其中每个我们的3个cassandra节点都有Spark。是正确的用户数据配置：
-totalnodes 0 --analyticsnodes 3
那么，我们将有0个仅包含cassandra的节点，以及3个具有Cassandra和Spark的节点？我们应该指定什么实例数？
4) We are interested in the use case where each of our 3 cassandra nodes has Spark. Is the proper user data configuration: --totalnodes 0 --analyticsnodes 3 Are then we going to have 0 nodes with only cassandra, and 3 nodes that have Cassandra and Spark? What is the Number of instances we should specify then?
5）在安装过程的第4步添加存储 ，我们被要求向实例添加存储。但是为什么我们需要这个存储空间？选择实例类型时，例如 m3.large ，我已经知道我的实例具有32GB的SSD存储，那又是什么呢？
5) In step 4 of installation process Add Storage, we are asked to add storage to the instance. But why do we need this storage? When choosing instance type, for example m3.large, I already know that my instance has 32GB of SSD storage, what is this then?
谢谢您的回答。如果有可以向我发送这些问题的电子邮件列表，我将不胜感激。
Thank you for your answers. If there is some email list to which I can send these questions, I would appreciate it.
推荐答案
使用AMI最高的那个版本号和您喜欢的虚拟化类型（-pv或-hvm）： http ：//docs.aws.amazon.com/AWSEC2/latest/UserGuide/virtualization_types.html
Use whichever AMI has the highest version number and the virtualization type you prefer (-pv or -hvm): http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/virtualization_types.html
您只需为EC2的使用付费。 DSE免费提供测试和开发。您无需申请试用许可证。如果您想要生产许可证或想成为启动成员，请联系DataStax。
You only pay for EC2 usage. DSE is free for testing and development. You do not need to request a trial license. If you want a production license or if you want to become a startup member, contact DataStax.
AMI将为每个 EC2实例安装一个 DSE节点。因此，如果要使用六节点群集，则需要指定6个实例。使用示例：
The AMI will install one "DSE node" per "EC2 instance". So if you want a six node cluster you need to specify 6 instances. To use your examples:
a）1个实例，--totalnodes 3（在用户数据中）
a) 1 instance, --totalnodes 3 (in the user data)
- 这不起作用
b）3个实例---taltalnodes 3
b) 3 instance, --tatalnodes 3
这将为您提供三个节点的Cassandra集群（在三个实例上运行）。您尚未指定搜索或分析节点，因此默认情况下，您只会获得Cassandra节点。
This will give you a three node Cassandra cluster (running on three instances). You have not specified search or analytics nodes so by default you will just get Cassandra nodes.
c）1个实例，--totalnodes 0 --analyticsnodes 3
c) 1 instance, --totalnodes 0 --analyticsnodes 3
不起作用。总节点数应等于实例数，并且分析节点数不能大于总节点数。
Won't work. Total nodes should equal number of instances and number of analytics nodes can't be greater than total nodes.
d）3个实例，--totalnodes 0 --analyticsnodes 3
d) 3 instance, --totalnodes 0 --analyticsnodes 3
不起作用。分析节点的数量不能大于总节点的数量。
Won't work. Number of analytics nodes can't be greater than number of total nodes.
如果您想要一个三节点集群，并且希望它们都同时运行Cassandra和Spark，请使用以下命令：
If you want a three-node cluster and you want all of them running both Cassandra and Spark use this:
3个实例，--totalnodes 3 --analyticsnodes 3
3 instances, --totalnodes 3 --analyticsnodes 3
添加存储是可选的。并且仅适用于某些实例类型。您应该注意到m3.large有一个默认配置，您实际上无法对其进行任何更改。
Adding storage is optional. And only possible with certain instance types. You should notice with m3.large that there is a default config and you can't actually make any changes to it.
希望这会有所帮助！
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