• ssl.client.auth=required If set to required client authentication is required. 如果设置，则要求客户端需要获得授权
• ssl.client.auth=requested This means client authentication is optional. unlike requested , if this option is set client can choose not to provide authentication information about itself意味着授权是可选的。不像requested，如果这样设置，客户端可以选择不提供授权信息
• ssl.client.auth=none This means client authentication is not needed.不需要授权

A string that is either "delete" or "compact". This string designates the retention policy to use on old log segments. The default policy ("delete") will discard old segments when their retention time or size limit has been reached. The "compact" setting will enable log compaction on the topic.

使用字符串表示，要么是“delete”要么是“compact”；此值表明了针对老日志的清除策略。默认策略是删除，即丢弃过期日志，一旦删除时间或者尺寸限制到了就会执行。“compact”设置会压缩待删除日志。

Specify the final compression type for a given topic. This configuration accepts the standard compression codecs ('gzip', 'snappy', lz4). It additionally accepts 'uncompressed' which is equivalent to no compression; and 'producer' which means retain the original compression codec set by the producer.

指定某个topic的消息的压缩格式。此配置接受标准化压缩编码器（‘gzip'，’snappy'，lz4）。也接受非压缩模式。’producer'意味着压缩编码器由producer设置。

The amount of time to retain delete tombstone markers for log compacted topics. This setting also gives a bound on the time in which a consumer must complete a read if they begin from offset 0 to ensure that they get a valid snapshot of the final stage (otherwise delete tombstones may be collected before they complete their scan)

对进行日志压缩的topics保存删除标记的时间长度.此设置给出了consumer必须从0开始阅读消息的时间区间，在此区间内，consumer可以阅读正确的消息快照，否则删除标记到了之后消息有可能已经删除，consumer也就无法获取正确的消息了。

The time to wait before deleting a file from the filesystem

从文件系统中删除前的等待时间

This setting allows specifying an interval at which we will force an fsync of data written to the log. For example if this was set to 1 we would fsync after every message; if it were 5 we would fsync after every five messages. In general we recommend you not set this and use replication for durability and allow the operating system's background flush capabilities as it is more efficient. This setting can be overridden on a per-topic basis (see the per-topic configuration section).

broker强制将消息回刷到磁盘日志文件的消息条数间隔。例如，如果设置为1，则每来一条消息都需要立刻写入磁盘。如果设置为5，则每来5条消息就会回刷消息进磁盘。一般来说，建议你不要更改这个值来确保消息可用性，而是使用备份机制提高消息可用性，允许操作系统的后台回刷能力更有效。这个设置可以是topic级别的。

This setting allows specifying a time interval at which we will force an fsync of data written to the log. For example if this was set to 1000 we would fsync after 1000 ms had passed. In general we recommend you not set this and use replication for durability and allow the operating system's background flush capabilities as it is more efficient.

强制broker将消息回刷到磁盘日志的时间间隔。例如，如果设置为1000，即每隔1000ms，回刷一次。一般来说，不建议你通过更改这个值来提供消息可用性，而是允许操作系统后台回刷能力，这样效率更高

A list of replicas for which log replication should be throttled on the follower side. The list should describe a set of replicas in the form [PartitionId]:[BrokerId],[PartitionId]:[BrokerId]:... or alternatively the wildcard '*' can be used to throttle all replicas for this topic.

在follower端进行限制的日志备份的备份列表。此表通过一个备份的集合展示：[PartitionId]:[BrokerId],[PartitionId]:[BrokerId]:... 或者是通配符‘＊’，可以用来限制topic的所有备份

This setting controls how frequently Kafka adds an index entry to it's offset index. The default setting ensures that we index a message roughly every 4096 bytes. More indexing allows reads to jump closer to the exact position in the log but makes the index larger. You probably don't need to change this

kafka向offset索引添加条目的频率。默认设置保证我们妹4096个字节对一条消息进行加索引。索引越多，在跳转时越容易跳转到正确的位置，但是也会增大索引的空间。一般不需要改变这个值

A list of replicas for which log replication should be throttled on the leader side. The list should describe a set of replicas in the form [PartitionId]:[BrokerId],[PartitionId]:[BrokerId]:... or alternatively the wildcard '*' can be used to throttle all replicas for this topic.

leader端进行限制的日志备份的备份列表。这个列表可以通过一个集合来展示：［PartittionId］：［BrokerId］，［PartitionId］：［BrokerId］,....或者通过通配符‘＊’来限制topic的所有的备份

This is largest message size Kafka will allow to be appended. Note that if you increase this size you must also increase your consumer's fetch size so they can fetch messages this large.

kafka broker可以追加的最大消息。注意，你可以提高这个值，与此同时，你也必须提高consumer可以消费的最大消息。

Specify the message format version the broker will use to append messages to the logs. The value should be a valid ApiVersion. Some examples are: 0.8.2, 0.9.0.0, 0.10.0, check ApiVersion for more details. By setting a particular message format version, the user is certifying that all the existing messages on disk are smaller or equal than the specified version. Setting this value incorrectly will cause consumers with older versions to break as they will receive messages with a format that they don't understand

指定broker可以追加的消息格式版本。此值应该是一个合法的APIVersion。一些例子如下：0.8.2，0.9.0.0，0.10.0，查看APIVersion可以获取更多细节。通过设置特定的消息格式版本，用户可以确认现存的消息格式版本都小于或者等于此版本号。设置不正确可能导致consumer无法解析消息。

The maximum difference allowed between the timestamp when a broker receives a message and the timestamp specified in the message. If message.timestamp.type=CreateTime, a message will be rejected if the difference in timestamp exceeds this threshold. This configuration is ignored if message.timestamp.type=LogAppendTime

broker收到消息的时间戳和消息中指定的时间戳之间的最大差值。如果message.timestamp.type＝CreateTime，如果这个差值大于此配置的话，消息会被拒收。如果message.timestamp.type＝LogAppendTIme，则此配置会被忽略

Define whether the timestamp in the message is message create time or log append time. The value should be either `CreateTime` or `LogAppendTime`

设定消息中的时间戳是创建时间还是日志追加时间。合法设置为‘CreateTime’或者‘LogAppendTime'

This configuration controls how frequently the log compactor will attempt to clean the log (assuminglog compaction is enabled). By default we will avoid cleaning a log where more than 50% of the log has been compacted. This ratio bounds the maximum space wasted in the log by duplicates (at 50% at most 50% of the log could be duplicates). A higher ratio will mean fewer, more efficient cleanings but will mean more wasted space in the log.

控制压缩器清除日志的频率（假定采用压缩机制）。more 情况下，如果超过50%的日志已经被压缩了，就暂时不用清除。这个比例控制日志浪费空间的大小（当压缩比例为50%时，最多浪费50%的空间）。此值越大，则清除效率越高，但是可能浪费更多空间。

The minimum time a message will remain uncompacted in the log. Only applicable for logs that are being compacted

保留为压缩日志的最短时间。只有日志压缩时才起作用

When used together, min.insync.replicas and acks allow you to enforce greater durability guarantees. A typical scenario would be to create a topic with a replication factor of 3, set min.insync.replicas to 2, and produce with acks of "all". This will ensure that the producer raises an exception if a majority of replicas do not receive a write.

当producer设置acks为‘all’或者‘－1’，min.insync.replicas指定备份的最小值：即一次写入需要多少个备份确认写入时才能被认为写入成功。如果没有达到这个最小值，则producer可能会出现异常（或者是NoEnoughReplicas或者是NotEnoughReplicasAfterAppend）。

当min.insync.replicas和acks一块使用时，可以提高可用性保证。典型的用法是备份数设置为3，min.insync.replicas设置为2，producer的‘acks’设置为‘all’，这样将保证producer在没有收到大多数备份成功写入消息时会抛出异常。

Should pre allocate file when create new segment?

是否预分配新日志文件

This configuration controls the maximum size a log can grow to before we will discard old log segments to free up space if we are using the "delete" retention policy. By default there is no size limit only a time limit.

日志删除之前的最大字节数。默认情况下没有尺寸限制

This configuration controls the maximum time we will retain a log before we will discard old log segments to free up space if we are using the "delete" retention policy. This represents an SLA on how soon consumers must read their data

日志删除之前保存的最长时间。

This configuration controls the segment file size for the log. Retention and cleaning is always done a file at a time so a larger segment size means fewer files but less granular control over retention

每个日志文件的最大字节数。删除和清除一般是在单个日志文件上展开的，如果日志文件越大，虽然可以减少文件数目，但是删除方面无法精确控制。

This configuration controls the size of the index that maps offsets to file positions. We preallocate this index file and shrink it only after log rolls. You generally should not need to change this setting

有关offsets和文件中位置的映射文件。一般是预分配这个文件，所以在存储目录中会发现无论何时，存储offsets和文件中位置的索引文件总是为10m。一般不需要更改这个文件。

The maximum random jitter subtracted from the scheduled segment roll time to avoid thundering herds of segment rolling

控制日志滚动时间时允许出现的最大随机抖动时间，这是因为日志滚动没有办法精确控制，因为涉及到检查日志滚动有时间间隔以及删除日志的原因。

This configuration controls the period of time after which Kafka will force the log to roll even if the segment file isn't full to ensure that retention can delete or compact old data

日志滚动的时间间隔，即使日志大小没有达到日志滚动时的大小限制。这个有利于过期日志删除以及日志压缩。

Indicates whether to enable replicas not in the ISR set to be elected as leader as a last resort, even though doing so may result in data loss

指明是否允许不在ISR中的备份节点是否允许被选为leader节点，当然这样有可能造成日志丢失