redis.conf AOF section comments improved.

[redis.git] / redis.conf

diff --git a/redis.conf b/redis.conf
index 5c16143c7c8aec618eb9dcdc34a5a16d506211b4..bcad01e003f0217213d9449c57638a5b69957052 100644 (file)
--- a/redis.conf
+++ b/redis.conf
@@ -114,6 +114,15 @@ stop-writes-on-bgsave-error yes
 # the dataset will likely be bigger if you have compressible values or keys.
 rdbcompression yes
 
+# Since verison 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
+
 # The filename where to dump the DB
 dbfilename dump.rdb
 
@@ -289,21 +298,23 @@ slave-read-only yes
 
 ############################## APPEND ONLY MODE ###############################
 
-# By default Redis asynchronously dumps the dataset on disk. If you can live
-# with the idea that the latest records will be lost if something like a crash
-# happens this is the preferred way to run Redis. If instead you care a lot
-# about your data and don't want to that a single record can get lost you should
-# enable the append only mode: when this mode is enabled Redis will append
-# every write operation received in the file appendonly.aof. This file will
-# be read on startup in order to rebuild the full dataset in memory.
+# By default Redis asynchronously dumps the dataset on disk. This mode is
+# good enough in many applications, but an issue with the Redis process or
+# a power outage may result into a few minutes of writes lost (depending on
+# the configured save points).
 #
-# Note that you can have both the async dumps and the append only file if you
-# like (you have to comment the "save" statements above to disable the dumps).
-# Still if append only mode is enabled Redis will load the data from the
-# log file at startup ignoring the dump.rdb file.
+# The Append Only File is an alternative persistence mode that provides
+# much better durability. For instance using the default data fsync policy
+# (see later in the config file) Redis can lose just one second of writes in a
+# dramatic event like a server power outage, or a single write if something
+# wrong with the Redis process itself happens, but the operating system is
+# still running correctly.
 #
-# IMPORTANT: Check the BGREWRITEAOF to check how to rewrite the append
-# log file in background when it gets too big.
+# AOF and RDB persistence can be enabled at the same time without problems.
+# If the AOF is enabled on startup Redis will load the AOF, that is the file
+# with the better durability guarantees.
+#
+# Please check http://redis.io/topics/persistence for more information.
 
 appendonly no
 
@@ -318,7 +329,7 @@ appendonly no
 #
 # no: don't fsync, just let the OS flush the data when it wants. Faster.
 # always: fsync after every write to the append only log . Slow, Safest.
-# everysec: fsync only if one second passed since the last fsync. Compromise.
+# everysec: fsync only one time every second. Compromise.
 #
 # The default is "everysec" that's usually the right compromise between
 # speed and data safety. It's up to you to understand if you can relax this to
@@ -328,6 +339,9 @@ appendonly no
 # or on the contrary, use "always" that's very slow but a bit safer than
 # everysec.
 #
+# More details please check the following article:
+# http://antirez.com/post/redis-persistence-demystified.html
+#
 # If unsure, use "everysec".
 
 # appendfsync always