需要澄清一些基本的 HDFS 术语
Need clarification for some basic HDFS terms
什么是镜像、检查点、什么是日志？
在我读过的一篇博客中 (link: http://www.aosabook.org/en/hdfs.html)，它说 HDFS 中的图像是 "the inode and the list of blocks that define the metadata of the name system"；我不确定这句话是什么意思...
他们还解释说 "checkpoint" 是 "the persistent record of image stored in the NameNode's local native filesystem"；在此声明中，"persistent record" 指的是什么？
期刊与这两个概念有什么关系？
在此先感谢您的帮助！
What is an image, a checkpoint, and what is a journal?
link...
上面描述的都非常清楚
Files and directories are represented on the NameNode by inodes. Inodes record attributes like permissions, modification and access times, namespace and disk space quotas.
The inodes and the list of blocks that define the metadata of the name system are called the image. [...] The persistent record of the image stored in the NameNode's local native filesystem is called a checkpoint.
The NameNode records changes to HDFS in a write-ahead log called the journal
关于您的其他问题
"the inode and the list of blocks that define the metadata of the name system"; I was not sure what this sentence means...
如果您读过什么是索引节点（和块），那么图像就是定义名称系统元数据的索引节点和块的集合……确实没有其他方式可以描述它。也许您需要查找元数据的定义？
what is referring to as a "persistent record"?
查找持久化的定义。检查点是图像在特定时间点的“快照”，存储在 HDFS 上。
how is journal related to those two concepts?
一个日志记录了HDFS的所有变化。写镜像和checkpoints的过程对HDFS做了改动
什么是镜像、检查点、什么是日志？
在我读过的一篇博客中 (link: http://www.aosabook.org/en/hdfs.html)，它说 HDFS 中的图像是 "the inode and the list of blocks that define the metadata of the name system"；我不确定这句话是什么意思...
他们还解释说 "checkpoint" 是 "the persistent record of image stored in the NameNode's local native filesystem"；在此声明中，"persistent record" 指的是什么？
期刊与这两个概念有什么关系？
在此先感谢您的帮助！
What is an image, a checkpoint, and what is a journal?
link...
上面描述的都非常清楚Files and directories are represented on the NameNode by inodes. Inodes record attributes like permissions, modification and access times, namespace and disk space quotas.
The inodes and the list of blocks that define the metadata of the name system are called the image. [...] The persistent record of the image stored in the NameNode's local native filesystem is called a checkpoint.
The NameNode records changes to HDFS in a write-ahead log called the journal
关于您的其他问题
"the inode and the list of blocks that define the metadata of the name system"; I was not sure what this sentence means...
如果您读过什么是索引节点（和块），那么图像就是定义名称系统元数据的索引节点和块的集合……确实没有其他方式可以描述它。也许您需要查找元数据的定义？
what is referring to as a "persistent record"?
查找持久化的定义。检查点是图像在特定时间点的“快照”，存储在 HDFS 上。
how is journal related to those two concepts?
一个日志记录了HDFS的所有变化。写镜像和checkpoints的过程对HDFS做了改动