redis.conf

Redis configuration file example

Note on units: when memory size is needed, it is possible to specify

it in the usual form of 1k 5GB 4M and so forth:

1k => 1000 bytes

1kb => 1024 bytes

1m => 1000000 bytes

1mb => 1024*1024 bytes

1g => 1000000000 bytes

1gb => 102410241024 bytes

units are case insensitive so 1GB 1Gb 1gB are all the same.

By default Redis does not run as a daemon. Use 'yes' if you need it.

Note that Redis will write a pid file in /var/run/redis.pid when daemonized.

daemonize no

When running daemonized, Redis writes a pid file in /var/run/redis.pid by

default. You can specify a custom pid file location here.

pidfile /var/run/redis.pid

Accept connections on the specified port, default is 6379.

If port 0 is specified Redis will not listen on a TCP socket.

port 6379

If you want you can bind a single interface, if the bind option is not

specified all the interfaces will listen for incoming connections.

bind 127.0.0.1

Specify the path for the unix socket that will be used to listen for

incoming connections. There is no default, so Redis will not listen

on a unix socket when not specified.

unixsocket /tmp/redis.sock

unixsocketperm 755

Close the connection after a client is idle for N seconds (0 to disable)

timeout 0

Set server verbosity to 'debug'

it can be one of:

debug (a lot of information, useful for development/testing)

verbose (many rarely useful info, but not a mess like the debug level)

notice (moderately verbose, what you want in production probably)

warning (only very important / critical messages are logged)

loglevel verbose

Specify the log file name. Also 'stdout' can be used to force

Redis to log on the standard output. Note that if you use standard

output for logging but daemonize, logs will be sent to /dev/null

logfile redis26x32_master_log_144

To enable logging to the system logger, just set 'syslog-enabled' to yes,

and optionally update the other syslog parameters to suit your needs.

syslog-enabled no

syslog-enabled yes

Specify the syslog identity.

syslog-ident redis

Specify the syslog facility. Must be USER or between LOCAL0-LOCAL7.

syslog-facility local0

Set the number of databases. The default database is DB 0, you can select

a different one on a per-connection basis using SELECT where

dbid is a number between 0 and 'databases'-1

databases 16

################################ SNAPSHOTTING #################################

Save the DB on disk:

save

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 at all commenting all the "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

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 an 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 usually even if there are problems with disk,

permissions, and so forth.

stop-writes-on-bgsave-error yes

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

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

The working directory.

The DB will be written inside this directory, with the filename specified

above using the 'dbfilename' configuration directive.

Also the Append Only File will be created inside this directory.

Note that you must specify a directory here, not a file name.

dir ./

################################# REPLICATION #################################

Master-Slave replication. Use slaveof to make a Redis instance a copy of

another Redis server. Note that the configuration is local to the slave

so for example it is possible to configure the slave to save the DB with a

different interval, or to listen to another port, and so on.

slaveof

If the master is password protected (using the "requirepass" configuration

directive below) it is possible to tell the slave to authenticate before

starting the replication synchronization process, otherwise the master will

refuse the slave request.

masterauth

When a slave lost the connection with the master, or when the replication

is still in progress, the slave can act in two different ways:

1) if slave-serve-stale-data is set to 'yes' (the default) the slave will

still reply to client requests, possibly with out of date data, or the

data set may just be empty if this is the first synchronization.

2) if slave-serve-stale data is set to 'no' the slave will reply with

an error "SYNC with master in progress" to all the kind of commands

but to INFO and SLAVEOF.

slave-serve-stale-data yes

You can configure a slave instance to accept writes or not. Writing against

a slave instance may be useful to store some ephemeral data (because data

written on a slave will be easily deleted after resync with the master) but

may also cause problems if clients are writing to it because of a

misconfiguration.

Since Redis 2.6 by default slaves are read-only.

Note: read only slaves are not designed to be exposed to untrusted clients

on the internet. It's just a protection layer against misuse of the instance.

Still a read only slave exports by default all the administrative commands

such as CONFIG, DEBUG, and so forth. To a limited extend you can improve

security of read only slaves using 'rename-command' to shadow all the

administrative / dangerous commands.

slave-read-only yes

Slaves send PINGs to server in a predefined interval. It's possible to change

this interval with the repl_ping_slave_period option. The default value is 10

seconds.

repl-ping-slave-period 10

The following option sets a timeout for both Bulk transfer I/O timeout and

master data or ping response timeout. The default value is 60 seconds.

It is important to make sure that this value is greater than the value

specified for repl-ping-slave-period otherwise a timeout will be detected

every time there is low traffic between the master and the slave.

repl-timeout 60

The slave priority is an integer number published by Redis in the INFO output.

It is used by Redis Sentinel in order to select a slave to promote into a

master if the master is no longer working correctly.

A slave with a low priority number is considered better for promotion, so

for instance if there are three slaves with priority 10, 100, 25 Sentinel will

pick the one wtih priority 10, that is the lowest.

However a special priority of 0 marks the slave as not able to perform the

role of master, so a slave with priority of 0 will never be selected by

Redis Sentinel for promotion.

By default the priority is 100.

slave-priority 100

################################## SECURITY ###################################

Require clients to issue AUTH before processing any other

commands. This might be useful in environments in which you do not trust

others with access to the host running redis-server.

This should stay commented out for backward compatibility and because most

people do not need auth (e.g. they run their own servers).

Warning: since Redis is pretty fast an outside user can try up to

150k passwords per second against a good box. This means that you should

use a very strong password otherwise it will be very easy to break.

requirepass foobared

Command renaming.

It is possible to change the name of dangerous commands in a shared

environment. For instance the CONFIG command may be renamed into something

of hard to guess so that it will be still available for internal-use

tools but not available for general clients.

Example:

rename-command CONFIG b840fc02d524045429941cc15f59e41cb7be6c52

It is also possible to completely kill a command renaming it into

an empty string:

rename-command CONFIG ""

################################### LIMITS ####################################

Set the max number of connected clients at the same time. By default

this limit is set to 10000 clients, however if the Redis server is not

able ot configure the process file limit to allow for the specified limit

the max number of allowed clients is set to the current file limit

minus 32 (as Redis reserves a few file descriptors for internal uses).

Once the limit is reached Redis will close all the new connections sending

an error 'max number of clients reached'.

maxclients 10000

Don't use more memory than the specified amount of bytes.

When the memory limit is reached Redis will try to remove keys

accordingly to the eviction policy selected (see maxmemmory-policy).

If Redis can't remove keys according to the policy, or if the policy is

set to 'noeviction', Redis will start to reply with errors to commands

that would use more memory, like SET, LPUSH, and so on, and will continue

to reply to read-only commands like GET.

This option is usually useful when using Redis as an LRU cache, or to set

an hard memory limit for an instance (using the 'noeviction' policy).

WARNING: If you have slaves attached to an instance with maxmemory on,

the size of the output buffers needed to feed the slaves are subtracted

from the used memory count, so that network problems / resyncs will

not trigger a loop where keys are evicted, and in turn the output

buffer of slaves is full with DELs of keys evicted triggering the deletion

of more keys, and so forth until the database is completely emptied.

In short... if you have slaves attached it is suggested that you set a lower

limit for maxmemory so that there is some free RAM on the system for slave

output buffers (but this is not needed if the policy is 'noeviction').

maxmemory

MAXMEMORY POLICY: how Redis will select what to remove when maxmemory

is reached? You can select among five behavior:

volatile-lru -> remove the key with an expire set using an LRU algorithm

allkeys-lru -> remove any key accordingly to the LRU algorithm

volatile-random -> remove a random key with an expire set

allkeys-random -> remove a random key, any key

volatile-ttl -> remove the key with the nearest expire time (minor TTL)

noeviction -> don't expire at all, just return an error on write operations

Note: with all the kind of policies, Redis will return an error on write

operations, when there are not suitable keys for eviction.

At the date of writing this commands are: set setnx setex append

incr decr rpush lpush rpushx lpushx linsert lset rpoplpush sadd

sinter sinterstore sunion sunionstore sdiff sdiffstore zadd zincrby

zunionstore zinterstore hset hsetnx hmset hincrby incrby decrby

getset mset msetnx exec sort

The default is:

maxmemory-policy volatile-lru

LRU and minimal TTL algorithms are not precise algorithms but approximated

algorithms (in order to save memory), so you can select as well the sample

size to check. For instance for default Redis will check three keys and

pick the one that was used less recently, you can change the sample size

using the following configuration directive.

maxmemory-samples 3

############################## APPEND ONLY MODE ###############################

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).

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.

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

The name of the append only file (default: "appendonly.aof")

appendfilename appendonly.aof

The fsync() call tells the Operating System to actually write data on disk

instead to wait for more data in the output buffer. Some OS will really flush

data on disk, some other OS will just try to do it ASAP.

Redis supports three different modes:

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 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

"no" that will let the operating system flush the output buffer when

it wants, for better performances (but if you can live with the idea of

some data loss consider the default persistence mode that's snapshotting),

or on the contrary, use "always" that's very slow but a bit safer than

everysec.

http://antirez.com/post/redis-persistence-demystified.html

If unsure, use "everysec".

appendfsync always

appendfsync everysec

appendfsync no

When the AOF fsync policy is set to always or everysec, and a background

saving process (a background save or AOF log background rewriting) is

performing a lot of I/O against the disk, in some Linux configurations

Redis may block too long on the fsync() call. Note that there is no fix for

this currently, as even performing fsync in a different thread will block

our synchronous write(2) call.

In order to mitigate this problem it's possible to use the following option

that will prevent fsync() from being called in the main process while a

BGSAVE or BGREWRITEAOF is in progress.

This means that while another child is saving the durability of Redis is

the same as "appendfsync none", that in practical terms means that it is

possible to lost up to 30 seconds of log in the worst scenario (with the

default Linux settings).

If you have latency problems turn this to "yes". Otherwise leave it as

"no" that is the safest pick from the point of view of durability.

no-appendfsync-on-rewrite no

Automatic rewrite of the append only file.

Redis is able to automatically rewrite the log file implicitly calling

BGREWRITEAOF when the AOF log size will growth by the specified percentage.

This is how it works: Redis remembers the size of the AOF file after the

latest rewrite (or if no rewrite happened since the restart, the size of

the AOF at startup is used).

This base size is compared to the current size. If the current size is

bigger than the specified percentage, the rewrite is triggered. Also

you need to specify a minimal size for the AOF file to be rewritten, this

is useful to avoid rewriting the AOF file even if the percentage increase

is reached but it is still pretty small.

Specify a percentage of zero in order to disable the automatic AOF

rewrite feature.

auto-aof-rewrite-percentage 100 auto-aof-rewrite-min-size 64mb

################################ LUA SCRIPTING ###############################

Max execution time of a Lua script in milliseconds.

If the maximum execution time is reached Redis will log that a script is

still in execution after the maximum allowed time and will start to

reply to queries with an error.

When a long running script exceed the maximum execution time only the

SCRIPT KILL and SHUTDOWN NOSAVE commands are available. The first can be

used to stop a script that did not yet called write commands. The second

is the only way to shut down the server in the case a write commands was

already issue by the script but the user don't want to wait for the natural

termination of the script.

Set it to 0 or a negative value for unlimited execution without warnings.

lua-time-limit 5000

################################## SLOW LOG ###################################

The Redis Slow Log is a system to log queries that exceeded a specified

execution time. The execution time does not include the I/O operations

like talking with the client, sending the reply and so forth,

but just the time needed to actually execute the command (this is the only

stage of command execution where the thread is blocked and can not serve

other requests in the meantime).

You can configure the slow log with two parameters: one tells Redis

what is the execution time, in microseconds, to exceed in order for the

command to get logged, and the other parameter is the length of the

slow log. When a new command is logged the oldest one is removed from the

queue of logged commands.

The following time is expressed in microseconds, so 1000000 is equivalent

to one second. Note that a negative number disables the slow log, while

a value of zero forces the logging of every command.

slowlog-log-slower-than 10000

There is no limit to this length. Just be aware that it will consume memory.

You can reclaim memory used by the slow log with SLOWLOG RESET.

slowlog-max-len 128

############################### ADVANCED CONFIG ###############################

Hashes are encoded using a memory efficient data structure when they have a

small number of entries, and the biggest entry does not exceed a given

threshold. These thresholds can be configured using the following directives.

hash-max-ziplist-entries 512 hash-max-ziplist-value 64

Similarly to hashes, small lists are also encoded in a special way in order

to save a lot of space. The special representation is only used when

you are under the following limits:

list-max-ziplist-entries 512 list-max-ziplist-value 64

Sets have a special encoding in just one case: when a set is composed

of just strings that happens to be integers in radix 10 in the range

of 64 bit signed integers.

The following configuration setting sets the limit in the size of the

set in order to use this special memory saving encoding.

set-max-intset-entries 512

Similarly to hashes and lists, sorted sets are also specially encoded in

order to save a lot of space. This encoding is only used when the length and

elements of a sorted set are below the following limits:

zset-max-ziplist-entries 128 zset-max-ziplist-value 64

Active rehashing uses 1 millisecond every 100 milliseconds of CPU time in

order to help rehashing the main Redis hash table (the one mapping top-level

keys to values). The hash table implementation Redis uses (see dict.c)

performs a lazy rehashing: the more operation you run into an hash table

that is rehashing, the more rehashing "steps" are performed, so if the

server is idle the rehashing is never complete and some more memory is used

by the hash table.

The default is to use this millisecond 10 times every second in order to

active rehashing the main dictionaries, freeing memory when possible.

If unsure:

use "activerehashing no" if you have hard latency requirements and it is

not a good thing in your environment that Redis can reply form time to time

to queries with 2 milliseconds delay.

use "activerehashing yes" if you don't have such hard requirements but

want to free memory asap when possible.

activerehashing yes

The client output buffer limits can be used to force disconnection of clients

that are not reading data from the server fast enough for some reason (a

common reason is that a Pub/Sub client can't consume messages as fast as the

publisher can produce them).

The limit can be set differently for the three different classes of clients:

normal -> normal clients

slave -> slave clients and MONITOR clients

pubsub -> clients subcribed to at least one pubsub channel or pattern

The syntax of every client-output-buffer-limit directive is the following:

client-output-buffer-limit

A client is immediately disconnected once the hard limit is reached, or if

the soft limit is reached and remains reached for the specified number of

seconds (continuously).

So for instance if the hard limit is 32 megabytes and the soft limit is

16 megabytes / 10 seconds, the client will get disconnected immediately

if the size of the output buffers reach 32 megabytes, but will also get

disconnected if the client reaches 16 megabytes and continuously overcomes

the limit for 10 seconds.

By default normal clients are not limited because they don't receive data

without asking (in a push way), but just after a request, so only

asynchronous clients may create a scenario where data is requested faster

than it can read.

Instead there is a default limit for pubsub and slave clients, since

subscribers and slaves receive data in a push fashion.

Both the hard or the soft limit can be disabled just setting it to zero.

client-output-buffer-limit normal 0 0 0 client-output-buffer-limit slave 256mb 64mb 60 client-output-buffer-limit pubsub 32mb 8mb 60