SNAPSHOTTING部分：
1.触发条件：
# Save the DB on disk:
# save <seconds> <changes>
# Will save the DB if both the given number of seconds and the given
# number of write operations against the DB occurred.
# In the example below the behaviour will be to save:
# after 900 sec (15 min) if at least 1 key changed
# after 300 sec (5 min) if at least 10 keys changed
# after 60 sec if at least 10000 keys changed
# Note: you can disable saving completely by commenting out all "save" lines.
# It is also possible to remove all the previously configured save
# points by adding a save directive with a single empty string argument
# like in the following example:
# save ""
save 900 1
save 300 10
save 60 10000
如果既定的秒数和给定的针对数据库的写操作次数均发生，则将保存数据库，在下面的示例中，行为将是保存：1）在900秒（15分钟）后，如果至少更改了1个键；2）300秒（5分钟）后，如果至少更改了10个按键；3）60秒后，如果至少更改了10000个键.您可以通过注释掉所有“保存”行来完全禁用保存。也可以通过添加带有单个空字符串参数的save指令来删除所有先前配置的保存点
这是持久化的触发条件，建议新手不要贸然更改持久化触发条件
2.报错停止写入：
# By default Redis will stop accepting writes if RDB snapshots are enabled
# (at least one save point) and the latest background save failed.
# This will make the user aware (in a hard way) that data is not persisting
# on disk properly, otherwise chances are that no one will notice and some
# disaster will happen.
#
# If the background saving process will start working again Redis will
# automatically allow writes again.
#
# However if you have setup your proper monitoring of the Redis server
# and persistence, you may want to disable this feature so that Redis will
# continue to work as usual even if there are problems with disk,
# permissions, and so forth.
stop-writes-on-bgsave-error yes
默认情况下，如果启用了RDB快照（至少一个保存点）并且最新的后台保存失败，则Redis将停止接受写入。 这将使用户（以一种强硬的方式）意识到数据无法正确地持久存储在磁盘上，否则，可能没人会注意到并且会发生一些灾难，如果后台保存过程将再次开始工作，则Redis将自动允许再次写入。但是，如果您设置了对Redis服务器和持久性的适当监视，则可能要禁用此功能，以便即使磁盘，权限等出现问题，Redis也将继续照常工作。
这个是一个很有意思的配置项，有点类似于别拿豆包不当干粮的配置项，通俗的说就是，我持久化失败了你redis也玩不了，你持久化好了我让redis马上正常工作，但是你如果设置了其他的监视，不需要我了，那么就当没有我，把我设置成no
3.数据压缩：
# Compress string objects using LZF when dump .rdb databases?
# For default that's set to 'yes' as it's almost always a win.
# If you want to save some CPU in the saving child set it to 'no' but
# the dataset will likely be bigger if you have compressible values or keys.
rdbcompression yes
指定存储至本地数据库时是否压缩数据，默认是yes，redis采用LZF压缩，如果为了节省CPU时间可以关闭该选项，但会导致数据库文件变的巨大.
4.持久化数据数量校验：
# Since version 5 of RDB a CRC64 checksum is placed at the end of the file.
# This makes the format more resistant to corruption but there is a performance
# hit to pay (around 10%) when saving and loading RDB files, so you can disable it
# for maximum performances.
#
# RDB files created with checksum disabled have a checksum of zero that will
# tell the loading code to skip the check.
rdbchecksum yes
从RDB版本5开始，CRC64校验数位于文件末尾。 这使该格式更能抵抗损坏，但是在保存和加载RDB文件时会降低性能（约10％），因此可以禁用该格式以获得最佳性能。在禁用校验和的情况下创建的RDB文件的校验和为零，这将指示加载代码跳过该校验。
5.文件名称：
# The filename where to dump the DB
dbfilename dump.rdb
6.文件目录：
# The working directory.
# The DB will be written inside this directory, with the filename specified
# above using the 'dbfilename' configuration directive.
# The Append Only File will also be created inside this directory.
# Note that you must specify a directory here, not a file name.
dir ./
数据库将被写入该目录内，文件名使用“ dbfilename”配置指令在上面指定。也将在此目录中创建附加文件。请注意，您必须在此处指定目录，而不是文件名。
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