# The size of the individual commitlog file segments. A commitlog
segment may be archived, deleted, or recycled once all the data
in it (potentially from each columnfamily in the system) has been
flushed to sstables.
commitlog_segment_size_in_mb是单次提交的日志文件段的大小。
当日志文件段里所有数据（可能来自系统中各个列族）都被刷到磁盘文件sstables中后，日志文件段就可以被存档，删除或者重复利用。
#
# The default size is 32, which is almost always fine, but if you are
# archiving commitlog segments (see commitlog_archiving.properties),
# then you probably want a finer granularity of archiving; 8 or 16 MB
# is reasonable.
默认大小是32MB，通常都很合适。
但是如果你开启了：日志文件段归档功能（详情见配置commitlog_archiving.properties）
这时候，你最好把值调成8或者16MB。
# Max mutation size is also configurable via max_mutation_size_in_kb setting in
# cassandra.yaml. The default is half the size commitlog_segment_size_in_mb * 1024.
# This should be positive and less than 2048.
另一个最大差异大小（大于它就要写盘了）在参数max_mutation_size_in_kb中定义，默认值
是commitlog_segment_size_in_mb大小的一般（乘1024，切换单位）
# NOTE: If max_mutation_size_in_kb is set explicitly then commitlog_segment_size_in_mb must
# be set to at least twice the size of max_mutation_size_in_kb / 1024
#
注意：如果max_mutation_size_in_kb这个值被明确设置了，那么commitlog_segment_size_in_mb也必须被设置
而commitlog_segment_size_in_mb至少要是max_mutation_size_in_kb / 1024的两倍
（也就是max_mutation_size是16M的话，commitlog_segment_size至少是32M）
commitlog_segment_size_in_mb: 32