Valkey and Redis OSS parameters Memcached specific parameters

Engine specific parameters

Valkey and Redis OSS

Most Valkey 8 parameters are compatible with Redis OSS 7.1 parameters. Valkey 7.2 parameters are the same as Redis OSS 7 parameters.

If you do not specify a parameter group for your Valkey or Redis OSS cluster, then a default parameter group appropriate to your engine version will be used. You can't change the values of any parameters in the default parameter group. However, you can create a custom parameter group and assign it to your cluster at any time as long as the values of conditionally modifiable parameters are the same in both parameter groups. For more information, see Creating an ElastiCache parameter group.

Valkey and Redis OSS parameters

Valkey 9.1 and Valkey 9.0 parameter changes

Parameter group family: valkey9

Note

Valkey 9.0 and above parameter groups are incompatible with Valkey 8.x and Redis OSS.

New parameter group families for Valkey 9.1 and Valkey 9.0:

default.valkey9 – Default parameter group for Valkey 9.1 and Valkey 9.0 (cluster mode disabled).
default.valkey9.cluster.on – Default parameter group for Valkey 9.1 and Valkey 9.0 with cluster mode enabled.

New customer-visible parameter in Valkey 9.0
Parameter	Description	Values	Default	Modifiable
`cluster-databases`	Number of databases available in cluster mode. Set at cluster creation time.	1 to 10,000	0	No (set at creation)

Valkey 8.2 parameter changes

Parameter group family: valkey8

Note

Valkey 8.2 parameter changes don't apply to Valkey 8.1
Valkey 8.0 and above parameter groups are incompatible with Redis OSS 7.2.4.
in Valkey 8.2, the following commands are unavailable for serverless caches: commandlog, commandlog get, commandlog help, commandlog len, and commandlog reset.

New parameter groups in Valkey 8.2
Name	Details	Description
search-fanout-target-mode (added in 8.2)	Default: client Type: string Modifiable: Yes Changes Take Effect: Immediately	The search-fanout-target-mode configuration parameter controls how search queries are distributed across nodes in a Valkey cluster environment. This setting accepts two values: "throughput" which optimizes for maximum throughput by randomly distributing search queries across all cluster nodes regardless of client type or READONLY status, and "client" which respects client connection characteristics by routing non-READONLY clients to primary nodes only, READONLY clients on replica connections to replica nodes only, and READONLY clients on primary connections randomly across all nodes. The default behavior is "client' mode, meaning the system will respect client connection types and READONLY status for query routing decisions. Use throughput mode for high-volume search workloads where maximum cluster resource utilization is desired, and client mode when you want to maintain read/write separation and respect application-level READONLY connection patterns.
search-default-timeout-ms	Default: 50000 Permitted values: 1 to 60000 Type: integer Modifiable: Yes Changes Take Effect: Immediately	The default Valkey search query timeout (in milliseconds).
search-enable-partial-results	Default: yes Permitted values: yes, no Type: boolean Modifiable: Yes Changes Take Effect: Immediately	Configures the query failure behavior for Valkey search. When enabled, search queries will return partial results if timeouts occur on one or more shards. When disabled, any shard timeout will cause the entire search query to fail and return an error.

Valkey 8.1 parameter changes

Parameter group family: valkey8

Note

Valkey 8.1 parameter changes don't apply to Valkey 8.0
Valkey 8.0 and above parameter groups are incompatible with Redis OSS 7.2.4.
in Valkey 8.1, the following commands are unavailable for serverless caches: commandlog, commandlog get, commandlog help, commandlog len, and commandlog reset.

New parameter groups in Valkey 8.1
Name	Details	Description
commandlog-request-larger-than (added in 8.1)	Default: 1048576 Type: integer Modifiable: Yes Changes Take Effect: Immediately	The maximum size, in bytes, for requests to be logged by the Valkey Command Log feature.
commandlog-large-request-max-len (added in 8.1)	Default: 128 Permitted values: 0-1024 Type: integer Modifiable: Yes Changes Take Effect: Immediately	The maximum length of the Valkey Command Log for requests.
commandlog-reply-larger-than (added in 8.1)	Default: 1048576 Type: integer Modifiable: Yes Changes Take Effect: Immediately	The maximum size, in bytes, for responses to be logged by the Valkey Command Log feature.
commandlog-large-reply-max-len (added in 8.1)	Default: 128 Permitted values: 0-1024 Type: integer Modifiable: Yes Changes Take Effect: Immediately	The maximum length of the Valkey Command Log for responses.

Valkey 8.0 parameter changes

Parameter group family: valkey8

Note

Redis OSS 7.2.4 is incompatible with Valkey 8 and above parameter groups.

Specific parameter changes in Valkey 8.0
Name	Details	Description
repl-backlog-size	Default: 10485760 Type: integer Modifiable: Yes Changes Take Effect: Immediately	The size, in bytes, of the primary node backlog buffer. The backlog is used for recording updates to data at the primary node. When a read replica connects to the primary, it attempts to perform a partial sync (psync), where it applies data from the backlog to catch up with the primary node. If the psync fails, then a full sync is required. The minimum value for this parameter is 16384. Note: Beginning with Redis OSS 2.8.22, this parameter applies to the primary cluster as well as the read replicas.
maxmemory-samples	Default: 3 Permitted values: 1 to 64 Type: integer Modifiable: Yes Changes Take Effect: Immediately	For least-recently-used (LRU) and time-to-live (TTL) calculations, this parameter represents the sample size of keys to check. By default, Redis OSS chooses 3 keys and uses the one that was used least recently.

New parameter groups in Valkey 8.0
Name	Details	Description
extended-redis-compatibility	Permitted values: yes, no Default: yes Type: boolean Modifiable: Yes Changes take place: immediately	Extended Redis OSS compatibility mode makes Valkey pretend to be Redis OSS 7.2. Enable this only if you have problems with tools or clients. Customer-facing impacts: `LOADING` - Redis OSS is loading the dataset in memory `BUSY` - Redis OSS is busy `MISCONF` - Redis OSS is configured in either of these ways: The `HELLO` command returns "server" => "redis" and "version" => "7.2.4" (our Redis OSS compatibility version). The `INFO` field for mode is called "redis_mode".

Removed parameter groups in Valkey 8.0
Name	Details	Description
lazyfree-lazy-eviction	Permitted values: yes, no Default: no Type: boolean Modifiable: Yes Changes take place: immediately	Performs an asynchronous delete on evictions.
lazyfree-lazy-expire	Permitted values: yes, no Default: no Type: boolean Modifiable: Yes Changes take place: immediately	Performs an asynchronous delete on expired keys.
lazyfree-lazy-server-del	Permitted values: yes, no Default: no Type: boolean Modifiable: Yes Changes take place: immediately	Performs an asynchronous delete for commands which update values.
lazyfree-lazy-user-del	Default: no Type: string Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster	When the value is set to yes, the DEL command acts the same as UNLINK.
replica-lazy-flush	Default: yes Type: boolean Modifiable: No Former name: slave-lazy-flush	Performs an asynchronous flushDB during replica sync.

Valkey 7.2 and Redis OSS 7 parameter changes

Parameter group family: valkey7

Valkey 7.2 default parameter groups are as follows:

default.valkey7 – Use this parameter group, or one derived from it, for Valkey (cluster mode disabled) clusters and replication groups.
default.valkey7.cluster.on – Use this parameter group, or one derived from it, for Valkey (cluster mode enabled) clusters and replication groups.

Parameter group family: redis7

Redis OSS 7 default parameter groups are as follows:

default.redis7 – Use this parameter group, or one derived from it, for Redis OSS (cluster mode disabled) clusters and replication groups.
default.redis7.cluster.on – Use this parameter group, or one derived from it, for Redis OSS (cluster mode enabled) clusters and replication groups.

Specific parameter changes

Parameters added in Redis OSS 7 are as follows. Valkey 7.2 also supports these parameters.

Name	Details	Description
`cluster-allow-pubsubshard-when-down`	Permitted values: `yes`, `no` Default: `yes` Type: string Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster.	When set to the default of yes, allows nodes to serve pubsub shard traffic while the cluster is in a down state, as long as it believes it owns the slots.
`cluster-preferred-endpoint-type`	Permitted values: `ip`, `tls-dynamic` Default: `tls-dynamic` Type: string Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster.	This value controls what endpoint is returned for MOVED/ASKING requests as well as the endpoint field for `CLUSTER SLOTS` and `CLUSTER SHARDS`. When the value is set to ip, the node will advertise its ip address. When the value is set to tls-dynamic, the node will advertise a hostname when encryption-in-transit is enabled and an ip address otherwise.
`latency-tracking`	Permitted values: `yes`, `no` Default: `no` Type: string Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster.	When set to yes tracks the per command latencies and enables exporting the percentile distribution via the `INFO` latency statistics command, and cumulative latency distributions (histograms) via the `LATENCY` command.
`hash-max-listpack-entries`	Permitted values: `0+` Default: `512` Type: integer Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster.	The maximum number of hash entries in order for the dataset to be compressed.
`hash-max-listpack-value`	Permitted values: `0+` Default: `64` Type: integer Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster.	The threshold of biggest hash entries in order for the dataset to be compressed.
`zset-max-listpack-entries`	Permitted values: `0+` Default: `128` Type: integer Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster.	The maximum number of sorted set entries in order for the dataset to be compressed.
`zset-max-listpack-value`	Permitted values: `0+` Default: `64` Type: integer Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster.	The threshold of biggest sorted set entries in order for the dataset to be compressed.

Parameters changed in Redis OSS 7 are as follows.

Name	Details	Description
`activerehashing`	Modifiable: `no`. In Redis OSS 7, this parameter is hidden and enabled by default. In order to disable it, you need to create a support case.	Modifiable was yes.

Parameters removed in Redis OSS 7 are as follows.

Name	Details	Description
`hash-max-ziplist-entries`	Permitted values: `0+` Default: `512` Type: integer Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster.	Use `listpack` instead of `ziplist` for representing small hash encoding
`hash-max-ziplist-value`	Permitted values: `0+` Default: `64` Type: integer Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster.	Use `listpack` instead of `ziplist` for representing small hash encoding
`zset-max-ziplist-entries`	Permitted values: `0+` Default: `128` Type: integer Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster.	Use `listpack` instead of `ziplist` for representing small hash encoding.
`zset-max-ziplist-value`	Permitted values: `0+` Default: `64` Type: integer Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster.	Use `listpack` instead of `ziplist` for representing small hash encoding.
`list-max-ziplist-size`	Permitted values: Default: `-2` Type: integer Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster.	The number of entries allowed per internal list node.

Redis OSS 6.x parameter changes

Parameter group family: redis6.x

Redis OSS 6.x default parameter groups are as follows:

default.redis6.x – Use this parameter group, or one derived from it, for Valkey or Redis OSS (cluster mode disabled) clusters and replication groups.
default.redis6.x.cluster.on – Use this parameter group, or one derived from it, for Valkey or Redis OSS (cluster mode enabled) clusters and replication groups.

Note

In Redis OSS engine version 6.2, when the r6gd node family was introduced for use with Data tiering in ElastiCache, only noeviction, volatile-lru and allkeys-lru max-memory policies are supported with r6gd node types.

For more information, see ElastiCache version 6.2 for Redis OSS (enhanced) and ElastiCache version 6.0 for Redis OSS (enhanced).

Parameters added in Redis OSS 6.x are as follows.

Details	Description
`acl-pubsub-default (added in 6.2)`	Permitted values: `resetchannels`, `allchannels` Default: `allchannels` Type: string Modifiable: Yes Changes take effect: The existing Redis OSS users associated to the cluster will continue to have existing permissions. Either update the users or reboot the cluster to update the existing Redis OSS users.	Default pubsub channel permissions for ACL users deployed to this cluster.
`cluster-allow-reads-when-down (added in 6.0)`	Default: no Type: string Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster	When set to yes, a Redis OSS (cluster mode enabled) replication group continues to process read commands even when a node is not able to reach a quorum of primaries. When set to the default of no, the replication group rejects all commands. We recommend setting this value to yes if you are using a cluster with fewer than three node groups or your application can safely handle stale reads.
`tracking-table-max-keys (added in 6.0)`	Default: 1,000,000 Type: number Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster	To assist client-side caching, Redis OSS supports tracking which clients have accessed which keys. When the tracked key is modified, invalidation messages are sent to all clients to notify them their cached values are no longer valid. This value enables you to specify the upper bound of this table. After this parameter value is exceeded, clients are sent invalidation randomly. This value should be tuned to limit memory usage while still keeping track of enough keys. Keys are also invalidated under low memory conditions.
`acllog-max-len (added in 6.0)`	Default: 128 Type: number Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster	This value corresponds to the max number of entries in the ACL log.
`active-expire-effort (added in 6.0)`	Default: 1 Type: number Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster	Redis OSS deletes keys that have exceeded their time to live by two mechanisms. In one, a key is accessed and is found to be expired. In the other, a periodic job samples keys and causes those that have exceeded their time to live to expire. This parameter defines the amount of effort that Redis OSS uses to expire items in the periodic job. The default value of 1 tries to avoid having more than 10 percent of expired keys still in memory. It also tries to avoid consuming more than 25 percent of total memory and to add latency to the system. You can increase this value up to 10 to increase the amount of effort spent on expiring keys. The tradeoff is higher CPU and potentially higher latency. We recommend a value of 1 unless you are seeing high memory usage and can tolerate an increase in CPU utilization.
`lazyfree-lazy-user-del (added in 6.0)`	Default: no Type: string Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster	When the value is set to yes, the `DEL` command acts the same as `UNLINK`.

Parameters removed in Redis OSS 6.x are as follows.

Name Details Description

Name	Details	Description
`lua-replicate-commands`	Permitted values: yes/no Default: yes Type: boolean Modifiable: Yes Changes take effect: Immediately	Always enable Lua effect replication or not in Lua scripts

lua-replicate-commands

Permitted values: yes/no

Default: yes

Type: boolean

Modifiable: Yes

Changes take effect: Immediately

Always enable Lua effect replication or not in Lua scripts

Redis OSS 5.0.3 parameter changes

Parameter group family: redis5.0

Redis OSS 5.0 default parameter groups

default.redis5.0 – Use this parameter group, or one derived from it, for Valkey or Redis OSS (cluster mode disabled) clusters and replication groups.
default.redis5.0.cluster.on – Use this parameter group, or one derived from it, for Valkey or Redis OSS (cluster mode enabled) clusters and replication groups.

Parameters added in Redis OSS 5.0.3
Name	Details	Description
`rename-commands`	Default: none Type: string Modifiable: Yes Changes take effect: Immediately across all nodes in the cluster	A space-separated list of renamed Redis OSS commands. The following is a restricted list of commands available for renaming: APPEND AUTH BITCOUNT BITFIELD BITOP BITPOS BLPOP BRPOP BRPOPLPUSH BZPOPMIN BZPOPMAX CLIENT CLUSTER COMMAND DBSIZE DECR DECRBY DEL DISCARD DUMP ECHO EVAL EVALSHA EXEC EXISTS EXPIRE EXPIREAT FLUSHALL FLUSHDB GEOADD GEOHASH GEOPOS GEODIST GEORADIUS GEORADIUSBYMEMBER GET GETBIT GETRANGE GETSET HDEL HEXISTS HGET HGETALL HINCRBY HINCRBYFLOAT HKEYS HLEN HMGET HMSET HSET HSETNX HSTRLEN HVALS INCR INCRBY INCRBYFLOAT INFO KEYS LASTSAVE LINDEX LINSERT LLEN LPOP LPUSH LPUSHX LRANGE LREM LSET LTRIM MEMORY MGET MONITOR MOVE MSET MSETNX MULTI OBJECT PERSIST PEXPIRE PEXPIREAT PFADD PFCOUNT PFMERGE PING PSETEX PSUBSCRIBE PUBSUB PTTL PUBLISH PUNSUBSCRIBE RANDOMKEY READONLY READWRITE RENAME RENAMENX RESTORE ROLE RPOP RPOPLPUSH RPUSH RPUSHX SADD SCARD SCRIPT SDIFF SDIFFSTORE SELECT SET SETBIT SETEX SETNX SETRANGE SINTER SINTERSTORE SISMEMBER SLOWLOG SMEMBERS SMOVE SORT SPOP SRANDMEMBER SREM STRLEN SUBSCRIBE SUNION SUNIONSTORE SWAPDB TIME TOUCH TTL TYPE UNSUBSCRIBE UNLINK UNWATCH WAIT WATCH ZADD ZCARD ZCOUNT ZINCRBY ZINTERSTORE ZLEXCOUNT ZPOPMAX ZPOPMIN ZRANGE ZRANGEBYLEX ZREVRANGEBYLEX ZRANGEBYSCORE ZRANK ZREM ZREMRANGEBYLEX ZREMRANGEBYRANK ZREMRANGEBYSCORE ZREVRANGE ZREVRANGEBYSCORE ZREVRANK ZSCORE ZUNIONSTORE SCAN SSCAN HSCAN ZSCAN XINFO XADD XTRIM XDEL XRANGE XREVRANGE XLEN XREAD XGROUP XREADGROUP XACK XCLAIM XPENDING GEORADIUS_RO GEORADIUSBYMEMBER_RO LOLWUT XSETID SUBSTR

For more information, see ElastiCache version 5.0.6 for Redis OSS (enhanced).

Redis OSS 5.0.0 parameter changes

Parameter group family: redis5.0

Redis OSS 5.0 default parameter groups

default.redis5.0 – Use this parameter group, or one derived from it, for Valkey or Redis OSS (cluster mode disabled) clusters and replication groups.
default.redis5.0.cluster.on – Use this parameter group, or one derived from it, for Valkey or Redis OSS (cluster mode enabled) clusters and replication groups.

Parameters added in Redis OSS 5.0
Name	Details	Description
`stream-node-max-bytes`	Permitted values: 0+ Default: 4096 Type: integer Modifiable: Yes Changes take effect: Immediately	The stream data structure is a radix tree of nodes that encode multiple items inside. Use this configuration to specify the maximum size of a single node in radix tree in Bytes. If set to 0, the size of the tree node is unlimited.
`stream-node-max-entries`	Permitted values: 0+ Default: 100 Type: integer Modifiable: Yes Changes take effect: Immediately	The stream data structure is a radix tree of nodes that encode multiple items inside. Use this configuration to specify the maximum number of items a single node can contain before switching to a new node when appending new stream entries. If set to 0, the number of items in the tree node is unlimited
`active-defrag-max-scan-fields`	Permitted values: 1 to 1000000 Default: 1000 Type: integer Modifiable: Yes Changes take effect: Immediately	Maximum number of set/hash/zset/list fields that will be processed from the main dictionary scan
`lua-replicate-commands`	Permitted values: yes/no Default: yes Type: boolean Modifiable: Yes Changes take effect: Immediately	Always enable Lua effect replication or not in Lua scripts
`replica-ignore-maxmemory`	Default: yes Type: boolean Modifiable: No	Determines if replica ignores `maxmemory` setting by not evicting items independent from the primary

Parameters changed in Redis OSS 5.0
Name	Details	Description
`active-defrag-cycle-min`	Permitted values: 1-75 Default: 5 Type: integer Modifiable: Yes Changes take place: immediately	Minimal effort for defrag in CPU percentage.

Redis OSS has renamed several parameters in engine version 5.0 in response to community feedback. For more information, see What's New in Redis OSS 5?. The following table lists the new names and how they map to previous versions.

Parameters renamed in Redis OSS 5.0
Name	Details	Description
`replica-lazy-flush`	Default: yes Type: boolean Modifiable: No Former name: slave-lazy-flush	Performs an asynchronous flushDB during replica sync.
`client-output-buffer-limit-replica-hard-limit`	Default: For values see Redis OSS node-type specific parameters Type: integer Modifiable: No Former name: client-output-buffer-limit-slave-hard-limit	For Redis OSS read replicas: If a client's output buffer reaches the specified number of bytes, the client will be disconnected.
`client-output-buffer-limit-replica-soft-limit`	Default: For values see Redis OSS node-type specific parameters Type: integer Modifiable: No Former name: client-output-buffer-limit-slave-soft-limit	For Redis OSS read replicas: If a client's output buffer reaches the specified number of bytes, the client will be disconnected, but only if this condition persists for `client-output-buffer-limit-replica-soft-seconds`.
`client-output-buffer-limit-replica-soft-seconds`	Default: 60 Type: integer Modifiable: No Former name: client-output-buffer-limit-slave-soft-seconds	For Redis OSS read replicas: If a client's output buffer remains at `client-output-buffer-limit-replica-soft-limit` bytes for longer than this number of seconds, the client will be disconnected.
`replica-allow-chaining`	Default: no Type: string Modifiable: No Former name: slave-allow-chaining	Determines whether a read replica in Redis OSS can have read replicas of its own.
`min-replicas-to-write`	Default: 0 Type: integer Modifiable: Yes Former name: min-slaves-to-write Changes Take Effect: Immediately	The minimum number of read replicas which must be available in order for the primary node to accept writes from clients. If the number of available replicas falls below this number, then the primary node will no longer accept write requests. If either this parameter or min-replicas-max-lag is 0, then the primary node will always accept writes requests, even if no replicas are available.
`min-replicas-max-lag`	Default: 10 Type: integer Modifiable: Yes Former name: min-slaves-max-lag Changes Take Effect: Immediately	The number of seconds within which the primary node must receive a ping request from a read replica. If this amount of time passes and the primary does not receive a ping, then the replica is no longer considered available. If the number of available replicas drops below min-replicas-to-write, then the primary will stop accepting writes at that point. If either this parameter or min-replicas-to-write is 0, then the primary node will always accept write requests, even if no replicas are available.
`close-on-replica-write`	Default: yes Type: boolean Modifiable: Yes Former name: close-on-slave-write Changes Take Effect: Immediately	If enabled, clients who attempt to write to a read-only replica will be disconnected.

Parameters removed in Redis OSS 5.0
Name	Details	Description
`repl-timeout`	Default: 60 Modifiable: No	Parameter is not available in this version.

Redis OSS 4.0.10 parameter changes

Parameter group family: redis4.0

Redis OSS 4.0.x default parameter groups

default.redis4.0 – Use this parameter group, or one derived from it, for Valkey or Redis OSS (cluster mode disabled) clusters and replication groups.
default.redis4.0.cluster.on – Use this parameter group, or one derived from it, for Valkey or Redis OSS (cluster mode enabled) clusters and replication groups.

Parameters changed in Redis OSS 4.0.10
Name	Details	Description
`maxmemory-policy`	Permitted values: `allkeys-lru`, `volatile-lru`, `allkeys-lfu`, `volatile-lfu`, `allkeys-random`, `volatile-random`, `volatile-ttl`, `noeviction` Default: volatile-lru Type: string Modifiable: Yes Changes take place: immediately	`maxmemory-policy` was added in version 2.6.13. In version 4.0.10 two new permitted values are added: `allkeys-lfu`, which will evict any key using approximated LFU, and `volatile-lfu`, which will evict using approximated LFU among the keys with an expire set. In version 6.2, when the r6gd node family was introduced for use with data-tiering, only `noeviction`, `volatile-lru` and `allkeys-lru` max-memory policies are supported with r6gd node types.

Parameters added in Redis OSS 4.0.10
Name	Details	Description
Async deletion parameters
`lazyfree-lazy-eviction`	Permitted values: yes/no Default: no Type: boolean Modifiable: Yes Changes take place: immediately	Performs an asynchronous delete on evictions.
`lazyfree-lazy-expire`	Permitted values: yes/no Default: no Type: boolean Modifiable: Yes Changes take place: immediately	Performs an asynchronous delete on expired keys.
`lazyfree-lazy-server-del`	Permitted values: yes/no Default: no Type: boolean Modifiable: Yes Changes take place: immediately	Performs an asynchronous delete for commands which update values.
`slave-lazy-flush`	Permitted values: N/A Default: no Type: boolean Modifiable: No Changes take place: N/A	Performs an asynchronous flushDB during slave sync.
LFU parameters
`lfu-log-factor`	Permitted values: any integer > 0 Default: 10 Type: integer Modifiable: Yes Changes take place: immediately	Set the log factor, which determines the number of key hits to saturate the key counter.
`lfu-decay-time`	Permitted values: any integer Default: 1 Type: integer Modifiable: Yes Changes take place: immediately	The amount of time in minutes to decrement the key counter.
Active defragmentation parameters
`activedefrag`	Permitted values: yes/no Default: no Type: boolean Modifiable: Yes Changes take place: immediately	Enables active defragmentation. Note In Valkey and Redis OSS versions 7.0 and above, AWS may automatically perform defragmentation when operationally necessary, regardless of this setting.
`active-defrag-ignore-bytes`	Permitted values: 10485760-104857600 Default: 104857600 Type: integer Modifiable: Yes Changes take place: immediately	Minimum amount of fragmentation waste to start active defrag.
`active-defrag-threshold-lower`	Permitted values: 1-100 Default: 10 Type: integer Modifiable: Yes Changes take place: immediately	Minimum percentage of fragmentation to start active defrag.
`active-defrag-threshold-upper`	Permitted values: 1-100 Default: 100 Type: integer Modifiable: Yes Changes take place: immediately	Maximum percentage of fragmentation at which we use maximum effort.
`active-defrag-cycle-min`	Permitted values: 1-75 Default: 25 Type: integer Modifiable: Yes Changes take place: immediately	Minimal effort for defrag in CPU percentage.
`active-defrag-cycle-max`	Permitted values: 1-75 Default: 75 Type: integer Modifiable: Yes Changes take place: immediately	Maximal effort for defrag in CPU percentage.
Client output buffer parameters
`client-query-buffer-limit`	Permitted values: 1048576-1073741824 Default: 1073741824 Type: integer Modifiable: Yes Changes take place: immediately	Max size of a single client query buffer.
`proto-max-bulk-len`	Permitted values: 1048576-536870912 Default: 536870912 Type: integer Modifiable: Yes Changes take place: immediately	Max size of a single element request.

Redis OSS 3.2.10 parameter changes

Parameter group family: redis3.2

ElastiCache for Redis OSS 3.2.10 there are no additional parameters supported.

Redis OSS 3.2.6 parameter changes

Parameter group family: redis3.2

For Redis OSS 3.2.6 there are no additional parameters supported.

Redis OSS 3.2.4 parameter changes

Parameter group family: redis3.2

Beginning with Redis OSS 3.2.4 there are two default parameter groups.

default.redis3.2 – When running Redis OSS 3.2.4, specify this parameter group or one derived from it, if you want to create a Valkey or Redis OSS (cluster mode disabled) replication group and still use the additional features of Redis OSS 3.2.4.
default.redis3.2.cluster.on – Specify this parameter group or one derived from it, when you want to create a Valkey or Redis OSS (cluster mode enabled) replication group.

Topics

New parameters for Redis OSS 3.2.4
Parameters changed in Redis OSS 3.2.4 (enhanced)

New parameters for Redis OSS 3.2.4

Parameter group family: redis3.2

For Redis OSS 3.2.4 the following additional parameters are supported.

Name	Details	Description
`list-max-ziplist-size`	Default: -2 Type: integer Modifiable: No	Lists are encoded in a special way to save space. The number of entries allowed per internal list node can be specified as a fixed maximum size or a maximum number of elements. For a fixed maximum size, use -5 through -1, meaning: -5: max size: 64 Kb - not recommended for normal workloads -4: max size: 32 Kb - not recommended -3: max size: 16 Kb - not recommended -2: max size: 8 Kb - recommended -1: max size: 4 Kb - recommended Positive numbers mean store up to exactly that number of elements per list node.
`list-compress-depth`	Default: 0 Type: integer Modifiable: Yes Changes Take Effect: Immediately	Lists may also be compressed. Compress depth is the number of quicklist ziplist nodes from each side of the list to exclude from compression. The head and tail of the list are always uncompressed for fast push and pop operations. Settings are: 0: Disable all compression. 1: Start compressing with the 1st node in from the head and tail. [head]->node->node->...->node->[tail] All nodes except [head] and [tail] compress. 2: Start compressing with the 2nd node in from the head and tail. [head]->[next]->node->node->...->node->[prev]->[tail] [head], [next], [prev], [tail] do not compress. All other nodes compress. Etc.
`cluster-enabled`	Default: no/yes * Type: string Modifiable: No	Indicates whether this is a Valkey or Redis OSS (cluster mode enabled) replication group in cluster mode (yes) or a Valkey or Redis OSS (cluster mode enabled) replication group in non-cluster mode (no). Valkey or Redis OSS (cluster mode enabled) replication groups in cluster mode can partition their data across up to 500 node groups. * Redis OSS 3.2.x has two default parameter groups. `default.redis3.2` – default value `no`. `default.redis3.2.cluster.on` – default value `yes`. .
`cluster-require-full-coverage`	Default: no Type: boolean Modifiable: yes Changes Take Effect: Immediately	When set to `yes`, Valkey or Redis OSS (cluster mode enabled) nodes in cluster mode stop accepting queries if they detect there is at least one hash slot uncovered (no available node is serving it). This way if the cluster is partially down, the cluster becomes unavailable. It automatically becomes available again as soon as all the slots are covered again. However, sometimes you want the subset of the cluster which is working to continue to accept queries for the part of the key space that is still covered. To do so, just set the `cluster-require-full-coverage` option to `no`.
`hll-sparse-max-bytes`	Default: 3000 Type: integer Modifiable: Yes Changes Take Effect: Immediately	HyperLogLog sparse representation bytes limit. The limit includes the 16 byte header. When a HyperLogLog using the sparse representation crosses this limit, it is converted into the dense representation. A value greater than 16000 is not recommended, because at that point the dense representation is more memory efficient. We recommend a value of about 3000 to have the benefits of the space-efficient encoding without slowing down PFADD too much, which is O(N) with the sparse encoding. The value can be raised to ~10000 when CPU is not a concern, but space is, and the data set is composed of many HyperLogLogs with cardinality in the 0 - 15000 range.
`reserved-memory-percent`	Default: 25 Type: integer Modifiable: Yes Changes Take Effect: Immediately	The percent of a node's memory reserved for nondata use. By default, the Redis OSS data footprint grows until it consumes all of the node's memory. If this occurs, then node performance will likely suffer due to excessive memory paging. By reserving memory, you can set aside some of the available memory for non-Redis OSS purposes to help reduce the amount of paging. This parameter is specific to ElastiCache, and is not part of the standard Redis OSS distribution. For more information, see `reserved-memory` and Managing reserved memory for Valkey and Redis OSS.

Parameters changed in Redis OSS 3.2.4 (enhanced)

Parameter group family: redis3.2

For Redis OSS 3.2.4 the following parameters were changed.

Name	Details	Change
`activerehashing`	Modifiable: Yes if the parameter group is not associated with any clusters. Otherwise, no.	Modifiable was No.
`databases`	Modifiable: Yes if the parameter group is not associated with any clusters. Otherwise, no.	Modifiable was No.
`appendonly`	Default: off Modifiable: No	If you want to upgrade from an earlier Redis OSS version, you must first turn `appendonly` off.
`appendfsync`	Default: off Modifiable: No	If you want to upgrade from an earlier Redis OSS version, you must first turn `appendfsync` off.
`repl-timeout`	Default: 60 Modifiable: No	Is now unmodifiable with a default of 60.
`tcp-keepalive`	Default: 300	Default was 0.
`list-max-ziplist-entries`		Parameter is no longer available.
`list-max-ziplist-value`		Parameter is no longer available.

Redis OSS 2.8.24 (enhanced) added parameters

Parameter group family: redis2.8

For Redis OSS 2.8.24 there are no additional parameters supported.

Redis OSS 2.8.23 (enhanced) added parameters

Parameter group family: redis2.8

For Redis OSS 2.8.23 the following additional parameter is supported.

Name Details Description

Name	Details	Description
`close-on-slave-write`	Default: yes Type: string (yes/no) Modifiable: Yes Changes Take Effect: Immediately	If enabled, clients who attempt to write to a read-only replica will be disconnected.

close-on-slave-write

Default: yes

Type: string (yes/no)

Modifiable: Yes

Changes Take Effect: Immediately

If enabled, clients who attempt to write to a read-only replica will be disconnected.

How close-on-slave-write works

The close-on-slave-write parameter is introduced by Amazon ElastiCache to give you more control over how your cluster responds when a primary node and a read replica node swap roles due to promoting a read replica to primary.

Image: close-on-replica-write, everything working fine

If the read-replica cluster is promoted to primary for any reason other than a Multi-AZ enabled replication group failing over, the client will continue trying to write to endpoint A. Because endpoint A is now the endpoint for a read-replica, these writes will fail. This is the behavior for Redis OSS before ElastiCache introducing close-on-replica-write and the behavior if you disable close-on-replica-write.

Image: close-on-slave-write, writes failing

With close-on-replica-write enabled, any time a client attempts to write to a read-replica, the client connection to the cluster is closed. Your application logic should detect the disconnection, check the DNS table, and reconnect to the primary endpoint, which now would be endpoint B.

Image: close-on-slave-write, writing to new primary cluster

When you might disable close-on-replica-write

If disabling close-on-replica-write results in writes to the failing cluster, why disable close-on-replica-write?

As previously mentioned, with close-on-replica-write enabled, any time a client attempts to write to a read-replica the client connection to the cluster is closed. Establishing a new connection to the node takes time. Thus, disconnecting and reconnecting as a result of a write request to the replica also affects the latency of read requests that are served through the same connection. This effect remains in place until a new connection is established. If your application is especially read-heavy or very latency-sensitive, you might keep your clients connected to avoid degrading read performance.

Redis OSS 2.8.22 (enhanced) added parameters

Parameter group family: redis2.8

For Redis OSS 2.8.22 there are no additional parameters supported.

Important

Beginning with Redis OSS version 2.8.22, repl-backlog-size applies to the primary cluster as well as to replica clusters.
Beginning with Redis OSS version 2.8.22, the repl-timeout parameter is not supported. If it is changed, ElastiCache will overwrite with the default (60s), as we do with appendonly.

The following parameters are no longer supported.

appendonly
appendfsync
repl-timeout

Redis OSS 2.8.21 added parameters

Parameter group family: redis2.8

For Redis OSS 2.8.21, there are no additional parameters supported.

Redis OSS 2.8.19 added parameters

Parameter group family: redis2.8

For Redis OSS 2.8.19 there are no additional parameters supported.

Redis OSS 2.8.6 added parameters

Parameter group family: redis2.8

For Redis OSS 2.8.6 the following additional parameters are supported.

Name Details Description

Name	Details	Description
`min-slaves-max-lag`	Default: 10 Type: integer Modifiable: Yes Changes Take Effect: Immediately	The number of seconds within which the primary node must receive a ping request from a read replica. If this amount of time passes and the primary does not receive a ping, then the replica is no longer considered available. If the number of available replicas drops below min-slaves-to-write, then the primary will stop accepting writes at that point. If either this parameter or min-slaves-to-write is 0, then the primary node will always accept writes requests, even if no replicas are available.
`min-slaves-to-write`	Default: 0 Type: integer Modifiable: Yes Changes Take Effect: Immediately	The minimum number of read replicas which must be available in order for the primary node to accept writes from clients. If the number of available replicas falls below this number, then the primary node will no longer accept write requests. If either this parameter or min-slaves-max-lag is 0, then the primary node will always accept writes requests, even if no replicas are available.
`notify-keyspace-events`	Default: (an empty string) Type: string Modifiable: Yes Changes Take Effect: Immediately	The types of keyspace events that Redis OSS can notify clients of. Each event type is represented by a single letter: K — Keyspace events, published with a prefix of __keyspace@<db>__ E — Key-event events, published with a prefix of __keyevent@<db>__ g — Generic, non-specific commands such as DEL, EXPIRE, RENAME, etc. $ — String commands l — List commands s — Set commands h — Hash commands z — Sorted set commands x — Expired events (events generated every time a key expires) e — Evicted events (events generated when a key is evicted for maxmemory) A — An alias for g$lshzxe Note: Include at least K or E in the string so that Amazon ElastiCache can deliver notifications. Event-type characters (such as `x` for expired events) identify what happened, but do not trigger delivery on their own. If you omit K and E, Amazon ElastiCache accepts the configuration without error, but silently disables notifications. You can have any combination of these event types. For example, AKE means that Redis OSS can publish notifications of all event types. Do not use any characters other than those listed above; attempts to do so will result in error messages. By default, this parameter is set to an empty string, meaning that keyspace event notification is disabled.
`repl-backlog-size`	Default: 1048576 Type: integer Modifiable: Yes Changes Take Effect: Immediately	The size, in bytes, of the primary node backlog buffer. The backlog is used for recording updates to data at the primary node. When a read replica connects to the primary, it attempts to perform a partial sync (`psync`), where it applies data from the backlog to catch up with the primary node. If the `psync` fails, then a full sync is required. The minimum value for this parameter is 16384. Note Beginning with Redis OSS 2.8.22, this parameter applies to the primary cluster as well as the read replicas.
`repl-backlog-ttl`	Default: 3600 Type: integer Modifiable: Yes Changes Take Effect: Immediately	The number of seconds that the primary node will retain the backlog buffer. Starting from the time the last replica node disconnected, the data in the backlog will remain intact until `repl-backlog-ttl` expires. If the replica has not connected to the primary within this time, then the primary will release the backlog buffer. When the replica eventually reconnects, it will have to perform a full sync with the primary. If this parameter is set to 0, then the backlog buffer will never be released.
`repl-timeout`	Default: 60 Type: integer Modifiable: Yes Changes Take Effect: Immediately	Represents the timeout period, in seconds, for: Bulk data transfer during synchronization, from the read replica's perspective Primary node timeout from the replica's perspective Replica timeout from the primary node's perspective

min-slaves-max-lag

Default: 10

Type: integer

Modifiable: Yes

Changes Take Effect: Immediately

The number of seconds within which the primary node must receive a ping request from a read replica. If this amount of time passes and the primary does not receive a ping, then the replica is no longer considered available. If the number of available replicas drops below min-slaves-to-write, then the primary will stop accepting writes at that point.

If either this parameter or min-slaves-to-write is 0, then the primary node will always accept writes requests, even if no replicas are available.

min-slaves-to-write

Default: 0

Type: integer

Modifiable: Yes

Changes Take Effect: Immediately

The minimum number of read replicas which must be available in order for the primary node to accept writes from clients. If the number of available replicas falls below this number, then the primary node will no longer accept write requests.

If either this parameter or min-slaves-max-lag is 0, then the primary node will always accept writes requests, even if no replicas are available.

notify-keyspace-events

Default: (an empty string)

Type: string

Modifiable: Yes

Changes Take Effect: Immediately

The types of keyspace events that Redis OSS can notify clients of. Each event type is represented by a single letter:

K — Keyspace events, published with a prefix of __keyspace@<db>__
E — Key-event events, published with a prefix of __keyevent@<db>__
g — Generic, non-specific commands such as DEL, EXPIRE, RENAME, etc.
$ — String commands
l — List commands
s — Set commands
h — Hash commands
z — Sorted set commands
x — Expired events (events generated every time a key expires)
e — Evicted events (events generated when a key is evicted for maxmemory)
A — An alias for g$lshzxe

Note: Include at least K or E in the string so that Amazon ElastiCache can deliver notifications. Event-type characters (such as x for expired events) identify what happened, but do not trigger delivery on their own. If you omit K and E, Amazon ElastiCache accepts the configuration without error, but silently disables notifications.

You can have any combination of these event types. For example, AKE means that Redis OSS can publish notifications of all event types.

Do not use any characters other than those listed above; attempts to do so will result in error messages.

By default, this parameter is set to an empty string, meaning that keyspace event notification is disabled.

repl-backlog-size

Default: 1048576

Type: integer

Modifiable: Yes

Changes Take Effect: Immediately

The size, in bytes, of the primary node backlog buffer. The backlog is used for recording updates to data at the primary node. When a read replica connects to the primary, it attempts to perform a partial sync (psync), where it applies data from the backlog to catch up with the primary node. If the psync fails, then a full sync is required.

The minimum value for this parameter is 16384.

Note

Beginning with Redis OSS 2.8.22, this parameter applies to the primary cluster as well as the read replicas.

repl-backlog-ttl

Default: 3600

Type: integer

Modifiable: Yes

Changes Take Effect: Immediately

The number of seconds that the primary node will retain the backlog buffer. Starting from the time the last replica node disconnected, the data in the backlog will remain intact until repl-backlog-ttl expires. If the replica has not connected to the primary within this time, then the primary will release the backlog buffer. When the replica eventually reconnects, it will have to perform a full sync with the primary.

If this parameter is set to 0, then the backlog buffer will never be released.

repl-timeout

Default: 60

Type: integer

Modifiable: Yes

Changes Take Effect: Immediately

Represents the timeout period, in seconds, for:

Bulk data transfer during synchronization, from the read replica's perspective
Primary node timeout from the replica's perspective
Replica timeout from the primary node's perspective

Redis OSS 2.6.13 parameters

Parameter group family: redis2.6

Redis OSS 2.6.13 was the first version of Redis OSS supported by ElastiCache. The following table shows the Redis OSS 2.6.13 parameters that ElastiCache supports.

Name	Details	Description
`activerehashing`	Default: yes Type: string (yes/no) Modifiable: Yes Changes take place: At Creation	Determines whether to enable Redis' active rehashing feature. The main hash table is rehashed ten times per second; each rehash operation consumes 1 millisecond of CPU time. This value is set when you create the parameter group. When assigning a new parameter group to a cluster, this value must be the same in both the old and new parameter groups.
`appendonly`	Default: no Type: string Modifiable: Yes Changes Take Effect: Immediately	Enables or disables Redis' append only file feature (AOF). AOF captures any Redis OSS commands that change data in the cache, and is used to recover from certain node failures. The default value is no, meaning AOF is turned off. Set this parameter to yes to enable AOF. For more information, see Mitigating Failures. Note Append Only Files (AOF) is not supported for cache.t2.* nodes. For nodes of this type, the `appendonly` parameter value is ignored. Note For Multi-AZ replication groups, AOF is not allowed.
`appendfsync`	Default: everysec Type: string Modifiable: Yes Changes Take Effect: Immediately	When `appendonly` is set to yes, controls how often the AOF output buffer is written to disk: no — the buffer is flushed to disk on an as-needed basis. everysec — the buffer is flushed once per second. This is the default. always — the buffer is flushed every time that data in the cluster is modified. Appendfsync is not supported for versions 2.8.22 and later.
`client-output-buffer-limit-normal-hard-limit`	Default: 0 Type: integer Modifiable: Yes Changes Take Effect: Immediately	If a client's output buffer reaches the specified number of bytes, the client will be disconnected. The default is zero (no hard limit).
`client-output-buffer-limit-normal-soft-limit`	Default: 0 Type: integer Modifiable: Yes Changes Take Effect: Immediately	If a client's output buffer reaches the specified number of bytes, the client will be disconnected, but only if this condition persists for `client-output-buffer-limit-normal-soft-seconds`. The default is zero (no soft limit).
`client-output-buffer-limit-normal-soft-seconds`	Default: 0 Type: integer Modifiable: Yes Changes Take Effect: Immediately	If a client's output buffer remains at `client-output-buffer-limit-normal-soft-limit` bytes for longer than this number of seconds, the client will be disconnected. The default is zero (no time limit).
`client-output-buffer-limit-pubsub-hard-limit`	Default: 33554432 Type: integer Modifiable: Yes Changes Take Effect: Immediately	For Redis OSS publish/subscribe clients: If a client's output buffer reaches the specified number of bytes, the client will be disconnected.
`client-output-buffer-limit-pubsub-soft-limit`	Default: 8388608 Type: integer Modifiable: Yes Changes Take Effect: Immediately	For Redis OSS publish/subscribe clients: If a client's output buffer reaches the specified number of bytes, the client will be disconnected, but only if this condition persists for `client-output-buffer-limit-pubsub-soft-seconds`.