Configuration reference

Basic parameters

• background
• custom_proc_title
• listen
• memtx_dir
• pid_file
• read_only
• vinyl_dir
• vinyl_timeout
• username
• wal_dir
• work_dir
• worker_pool_threads

background

Since version 1.6.2. Run the server as a background task. The log and pid_file parameters must be non-null for this to work.

Type: boolean

Default: false

Dynamic: no

custom_proc_title

Since version 1.6.7. Add the given string to the server’s process title (what’s shown in the COMMAND column for ps -ef and top -c commands).

For example, ordinarily ps -ef shows the Tarantool server process thus:

$ ps -ef | grep tarantool
1000     14939 14188  1 10:53 pts/2    00:00:13 tarantool <running>

But if the configuration parameters include custom_proc_title='sessions' then the output looks like:

$ ps -ef | grep tarantool
1000     14939 14188  1 10:53 pts/2    00:00:16 tarantool <running>: sessions

Type: string

Default: null

Dynamic: yes

listen

Since version 1.6.4. The read/write data port number or URI (Universal Resource Identifier) string. Has no default value, so must be specified if connections will occur from remote clients that do not use the “admin port”. Connections made with listen = URI are called “binary port” or “binary protocol” connections.

A typical value is 3301.

Note

A replica also binds to this port, and accepts connections, but these connections can only serve reads until the replica becomes a master.

Type: integer or string

Default: null

Dynamic: yes

memtx_dir

Since version 1.7.4. A directory where memtx stores snapshot (.snap) files. Can be relative to work_dir. If not specified, defaults to work_dir. See also wal_dir.

Type: string

Default: “.”

Dynamic: no

pid_file

Since version 1.4.9. Store the process id in this file. Can be relative to work_dir. A typical value is “tarantool.pid”.

Type: string

Default: null

Dynamic: no

read_only

Since version 1.7.1. Say box.cfg{read_only=true...} to put the server instance in read-only mode. After this, any requests that try to change persistent data will fail with error ER_READONLY. Read-only mode should be used for master-replica replication. Read-only mode does not affect data-change requests for spaces defined as temporary. Although read-only mode prevents the server from writing to the WAL, it does not prevent writing diagnostics with the log module.

Type: boolean

Default: false

Dynamic: yes

Setting read_only == true affects spaces differently depending on the options that were used during box.schema.space.create.

vinyl_dir

Since version 1.7.1. A directory where vinyl files or subdirectories will be stored. Can be relative to work_dir. If not specified, defaults to work_dir.

Type: string

Default: “.”

Dynamic: no

vinyl_timeout

Since version 1.7.5. The vinyl storage engine has a scheduler which does compaction. When vinyl is low on available memory, the compaction scheduler may be unable to keep up with incoming update requests. In that situation, queries may time out after vinyl_timeout seconds. This should rarely occur, since normally vinyl would throttle inserts when it is running low on compaction bandwidth. Compaction can also be ordered manually with index_object:compact().

Type: float

Default: 60

Dynamic: yes

username

Since version 1.4.9. UNIX user name to switch to after start.

Type: string

Default: null

Dynamic: no

wal_dir

Since version 1.6.2. A directory where write-ahead log (.xlog) files are stored. Can be relative to work_dir. Sometimes wal_dir and memtx_dir are specified with different values, so that write-ahead log files and snapshot files can be stored on different disks. If not specified, defaults to work_dir.

Type: string

Default: “.”

Dynamic: no

work_dir

Since version 1.4.9. A directory where database working files will be stored. The server instance switches to work_dir with chdir(2) after start. Can be relative to the current directory. If not specified, defaults to the current directory. Other directory parameters may be relative to work_dir, for example:

box.cfg{
    work_dir = '/home/user/A',
    wal_dir = 'B',
    memtx_dir = 'C'
}

will put xlog files in /home/user/A/B, snapshot files in /home/user/A/C, and all other files or subdirectories in /home/user/A.

Type: string

Default: null

Dynamic: no

worker_pool_threads

Since version 1.7.5. The maximum number of threads to use during execution of certain internal processes (currently socket.getaddrinfo() and coio_call()).

Type: integer

Default: 4

Dynamic: yes

Configuring the storage

• memtx_memory
• memtx_max_tuple_size
• memtx_min_tuple_size
• vinyl_bloom_fpr
• vinyl_cache
• vinyl_max_tuple_size
• vinyl_memory
• vinyl_page_size
• vinyl_range_size
• vinyl_run_count_per_level
• vinyl_run_size_ratio
• vinyl_read_threads
• vinyl_write_threads

memtx_memory

Since version 1.7.4. How much memory Tarantool allocates to actually store tuples. When the limit is reached, INSERT or UPDATE requests begin failing with error ER_MEMORY_ISSUE. The server does not go beyond the memtx_memory limit to allocate tuples, but there is additional memory used to store indexes and connection information. Depending on actual configuration and workload, Tarantool can consume up to 20% more than the memtx_memory limit.

Type: float

Default: 256 * 1024 * 1024 = 268435456 bytes

Dynamic: yes but it cannot be decreased

memtx_max_tuple_size

Since version 1.7.4. Size of the largest allocation unit, for the memtx storage engine. It can be increased if it is necessary to store large tuples. See also: vinyl_max_tuple_size.

Type: integer

Default: 1024 * 1024 = 1048576 bytes

Dynamic: no

memtx_min_tuple_size

Since version 1.7.4. Size of the smallest allocation unit. It can be decreased if most of the tuples are very small. The value must be between 8 and 1048280 inclusive.

Type: integer

Default: 16 bytes

Dynamic: no

vinyl_bloom_fpr

Since version 1.7.4. Bloom filter false positive rate – the suitable probability of the bloom filter to give a wrong result. The vinyl_bloom_fpr setting is a default value for one of the options in the Options for space_object:create_index() chart.

Type: float

Default = 0.05

Dynamic: no

vinyl_cache

Since version 1.7.4. The cache size for the vinyl storage engine. The cache can be resized dynamically.

Type: integer

Default = 128 * 1024 * 1024 = 134217728 bytes

Dynamic: yes

vinyl_max_tuple_size

Since version 1.7.5. Size of the largest allocation unit, for the vinyl storage engine. It can be increased if it is necessary to store large tuples. See also: memtx_max_tuple_size.

Type: integer

Default: 1024 * 1024 = 1048576 bytes

Dynamic: no

vinyl_memory

Since version 1.7.4. The maximum number of in-memory bytes that vinyl uses.

Type: integer

Default = 128 * 1024 * 1024 = 134217728 bytes

Dynamic: yes but it cannot be decreased

vinyl_page_size

Since version 1.7.4. Page size. Page is a read/write unit for vinyl disk operations. The vinyl_page_size setting is a default value for one of the options in the Options for space_object:create_index() chart.

Type: integer

Default = 8 * 1024 = 8192 bytes

Dynamic: no

vinyl_range_size

Since version 1.7.4. The default maximum range size for a vinyl index. The maximum range size affects the decision whether to split a range.

If vinyl_range_size is not nil and not 0, then it is used as the default value for the range_size option in the Options for space_object:create_index() chart.

If vinyl_range_size is nil or 0, and range_size is not specified when the index is created, then Tarantool sets a value later depending on performance considerations. To see the actual value, use index_object:stat().range_size.

In Tarantool versions prior to 1.10.2, vinyl_range_size default value was 1073741824.

Type: integer

Default = nil bytes

Dynamic: no

vinyl_run_count_per_level

Since version 1.7.4. The maximal number of runs per level in vinyl LSM tree. If this number is exceeded, a new level is created. The vinyl_run_count_per_level setting is a default value for one of the options in the Options for space_object:create_index() chart.

Type: integer

Default = 2

Dynamic: no

vinyl_run_size_ratio

Since version 1.7.4. Ratio between the sizes of different levels in the LSM tree. The vinyl_run_size_ratio setting is a default value for one of the options in the Options for space_object:create_index() chart.

Type: float

Default = 3.5

Dynamic: no

vinyl_read_threads

Since version 1.7.5. The maximum number of read threads that vinyl can use for some concurrent operations, such as I/O and compression.

Type: integer

Default = 1

Dynamic: no

vinyl_write_threads

Since version 1.7.5. The maximum number of write threads that vinyl can use for some concurrent operations, such as I/O and compression.

Type: integer

Default = 2

Dynamic: no

Checkpoint daemon

• checkpoint_count
• checkpoint_interval

The checkpoint daemon is a fiber which is constantly running. At intervals, it may make new snapshot (.snap) files and then may delete old snapshot files.

The checkpoint_interval and checkpoint_count configuration settings determine how long the intervals are, and how many snapshots should exist before deletions occur.

Tarantool garbage collector

The checkpoint daemon may activate the Tarantool garbage collector which deletes old files. This garbage collector is distinct from the Lua garbage collector which is for Lua objects, and distinct from a Tarantool garbage collector which specializes in handling shard buckets.

If the checkpoint daemon deletes an old snapshot file, then the Tarantool garbage collector will also delete any write-ahead log (.xlog) files which are older than the snapshot file and which contain information that is present in the snapshot file. It will also delete obsolete vinyl .run files.

The checkpoint daemon and the Tarantool garbage collector will not delete a file if:

• a backup is ongoing and the file has not been backed up (see “Hot backup”), or
• replication is ongoing and the file has not been relayed to a replica (see “Replication architecture”),
• a replica is connecting, or
• a replica has fallen behind. The progress of each replica is tracked; if a replica’s position is far from being up to date, then the server stops to give it a chance to catch up. If an administrator concludes that a replica is permanently down, then the correct procedure is to restart the server, or (preferably) remove the replica from the cluster.

checkpoint_interval

Since version 1.7.4. The interval between actions by the checkpoint daemon, in seconds. If checkpoint_interval is set to a value greater than zero, and there is activity which causes change to a database, then the checkpoint daemon will call box.snapshot() every checkpoint_interval seconds, creating a new snapshot file each time. If checkpoint_interval is set to zero, then the checkpoint daemon is disabled.

For example:

box.cfg{checkpoint_interval=60}

will cause the checkpoint daemon to create a new database snapshot once per minute, if there is activity.

Type: integer

Default: 3600 (one hour)

Dynamic: yes

checkpoint_count

Since version 1.7.4. The maximum number of snapshots that may exist on the memtx_dir directory before the checkpoint daemon will delete old snapshots. If checkpoint_count equals zero, then the checkpoint daemon does not delete old snapshots. For example:

box.cfg{
    checkpoint_interval = 3600,
    checkpoint_count  = 10
}

will cause the checkpoint daemon to create a new snapshot each hour until it has created ten snapshots. After that, it will delete the oldest snapshot (and any associated write-ahead-log files) after creating a new one.

Remember that, as noted earlier, snapshots will not be deleted if replication is ongoing and the file has not been relayed to a replica. Therefore checkpoint_count has no effect unless all replicas are alive.

Type: integer

Default: 2

Dynamic: yes

Binary logging and snapshots

• force_recovery,
• rows_per_wal,
• wal_max_size,
• snap_io_rate_limit,
• wal_mode,
• wal_dir_rescan_delay

force_recovery

Since version 1.7.4. If force_recovery equals true, Tarantool tries to continue if there is an error while reading a snapshot file (at server instance start) or a write-ahead log file (at server instance start or when applying an update at a replica): skips invalid records, reads as much data as possible and lets the process finish with a warning. Users can prevent the error from recurring by writing to the database and executing box.snapshot().

Otherwise, Tarantool aborts recovery if there is an error while reading.

Type: boolean

Default: false

Dynamic: no

rows_per_wal

Since version 1.6.2. How many log records to store in a single write-ahead log file. When this limit is reached, Tarantool creates another WAL file named <first-lsn-in-wal>.xlog. This can be useful for simple rsync-based backups.

Type: integer

Default: 500000

Dynamic: no

wal_max_size

Since version 1.7.4. The maximum number of bytes in a single write-ahead log file. When a request would cause an .xlog file to become larger than wal_max_size, Tarantool creates another WAL file – the same effect that happens when the rows_per_wal limit is reached.

Type: integer

Default: 268435456 (256 * 1024 * 1024) bytes

Dynamic: no

snap_io_rate_limit

Since version 1.4.9. Reduce the throttling effect of box.snapshot() on INSERT/UPDATE/DELETE performance by setting a limit on how many megabytes per second it can write to disk. The same can be achieved by splitting wal_dir and memtx_dir locations and moving snapshots to a separate disk. The limit also affects what box.stat.vinyl().regulator may show for the write rate of dumps to .run and .index files.

Type: float

Default: null

Dynamic: yes

wal_mode

Since version 1.6.2. Specify fiber-WAL-disk synchronization mode as:

• none: write-ahead log is not maintained;
• write: fibers wait for their data to be written to the write-ahead log (no fsync(2));
• fsync: fibers wait for their data, fsync(2) follows each write(2);

Type: string

Default: “write”

Dynamic: no

wal_dir_rescan_delay

Since version 1.6.2. Number of seconds between periodic scans of the write-ahead-log file directory, when checking for changes to write-ahead-log files for the sake of replication or hot standby.

Type: float

Default: 2

Dynamic: no

Hot standby

hot_standby

Since version 1.7.4. Whether to start the server in hot standby mode.

Hot standby is a feature which provides a simple form of failover without replication.

The expectation is that there will be two instances of the server using the same configuration. The first one to start will be the “primary” instance. The second one to start will be the “standby” instance.

To initiate the standby instance, start a second instance of the Tarantool server on the same computer with the same box.cfg configuration settings – including the same directories and same non-null URIs – and with the additional configuration setting hot_standby = true. Expect to see a notification ending with the words I> Entering hot standby mode. This is fine. It means that the standby instance is ready to take over if the primary instance goes down.

The standby instance will initialize and will try to take a lock on wal_dir, but will fail because the primary instance has made a lock on wal_dir. So the standby instance goes into a loop, reading the write ahead log which the primary instance is writing (so the two instances are always in sync), and trying to take the lock. If the primary instance goes down for any reason, the lock will be released. In this case, the standby instance will succeed in taking the lock, will connect on the listen address and will become the primary instance. Expect to see a notification ending with the words I> ready to accept requests.

Thus there is no noticeable downtime if the primary instance goes down.

Hot standby feature has no effect:

• if wal_dir_rescan_delay = a large number (on Mac OS and FreeBSD); on these platforms, it is designed so that the loop repeats every wal_dir_rescan_delay seconds.
• if wal_mode = ‘none’; it is designed to work with wal_mode = 'write' or wal_mode = 'fsync'.
• for spaces created with engine = ‘vinyl’; it is designed to work for spaces created with engine = 'memtx'.

Type: boolean

Default: false

Dynamic: no

Replication

• replication
• replication_connect_timeout
• replication_connect_quorum
• replication_skip_conflict
• replication_sync_lag
• replication_sync_timeout
• replication_timeout
• replicaset_uuid
• instance_uuid

replication

Since version 1.7.4. If replication is not an empty string, the instance is considered to be a Tarantool replica. The replica will try to connect to the master specified in replication with a URI (Universal Resource Identifier), for example:

konstantin:secret_password@tarantool.org:3301

If there is more than one replication source in a replica set, specify an array of URIs, for example (replace ‘uri’ and ‘uri2’ in this example with valid URIs):

box.cfg{ replication = { ‘uri1’, ‘uri2’ } }

If one of the URIs is “self” – that is, if one of the URIs is for the instance where box.cfg{} is being executed on – then it is ignored. Thus it is possible to use the same replication specification on multiple server instances, as shown in these examples.

The default user name is ‘guest’.

A read-only replica does not accept data-change requests on the listen port.

The replication parameter is dynamic, that is, to enter master mode, simply set replication to an empty string and issue:

box.cfg{ replication = new-value }

Type: string

Default: null

Dynamic: yes

replication_connect_timeout

Since version 1.9.0. The number of seconds that a replica will wait when trying to connect to a master in a cluster. See orphan status for details.

This parameter is different from replication_timeout, which a master uses to disconnect a replica when the master receives no acknowledgments of heartbeat messages.

Type: float

Default: 30

Dynamic: yes

replication_connect_quorum

Since version 1.9.0. By default a replica will try to connect to all the masters, or it will not start. (The default is recommended so that all replicas will receive the same replica set UUID.)

However, by specifying replication_connect_quorum = N, where N is a number greater than or equal to zero, users can state that the replica only needs to connect to N masters.

This parameter has effect during bootstrap and during configuration update. Setting replication_connect_quorum = 0 makes Tarantool require no immediate reconnect only in case of recovery. See orphan status for details.

Example:

box.cfg{replication_connect_quorum=2}

Type: integer

Default: null

Dynamic: yes

replication_skip_conflict

Since version 1.10.1. By default, if a replica adds a unique key that another replica has added, replication stops with error = ER_TUPLE_FOUND.

However, by specifying replication_skip_conflict = true, users can state that such errors may be ignored.

Example:

box.cfg{replication_skip_conflict=true}

Type: boolean

Default: false

Dynamic: yes

replication_sync_lag

Since version 1.9.0. The maximum lag allowed for a replica. When a replica syncs (gets updates from a master), it may not catch up completely. The number of seconds that the replica is behind the master is called the “lag”. Syncing is considered to be complete when the replica’s lag is less than or equal to replication_sync_lag.

If a user sets replication_sync_lag to nil or to 365 * 100 * 86400 (TIMEOUT_INFINITY), then lag does not matter – the replica is always considered to be “synced”. Also, the lag is ignored (assumed to be infinite) in case the master is running Tarantool older than 1.7.7, which does not send heartbeat messages.

This parameter is ignored during bootstrap. See orphan status for details.

Type: float

Default: 10

Dynamic: yes

replication_sync_timeout

Since version 1.10.2. The number of seconds that a replica will wait when trying to sync with a master in a cluster, or a quorum of masters, after connecting or during configuration update. This could fail indefinitely if replication_sync_lag is smaller than network latency, or if the replica cannot keep pace with master updates. If replication_sync_timeout expires, the replica enters orphan status.

Type: float

Default: 300

Dynamic: yes

replication_timeout

Since version 1.7.5. If the master has no updates to send to the replicas, it sends heartbeat messages every replication_timeout seconds, and each replica sends an ACK packet back.

Both master and replicas are programmed to drop the connection if they get no response in four replication_timeout periods. If the connection is dropped, a replica tries to reconnect to the master.

See more in Monitoring a replica set.

Type: integer

Default: 1

Dynamic: yes

replicaset_uuid

Since version 1.9.0. As described in section “Replication architecture”, each replica set is identified by a universally unique identifier called replica set UUID, and each instance is identified by an instance UUID.

Ordinarily it is sufficient to let the system generate and format the UUID strings which will be permanently stored.

However, some administrators may prefer to store Tarantool configuration information in a central repository, for example Apache ZooKeeper. Such administrators can assign their own UUID values for either – or both – instances (instance_uuid) and replica set (replicaset_uuid), when starting up for the first time.

General rules:

• The values must be true unique identifiers, not shared by other instances or replica sets within the common infrastructure.
• The values must be used consistently, not changed after initial setup (the initial values are stored in snapshot files and are checked whenever the system is restarted).
• The values must comply with RFC 4122. The nil UUID is not allowed.

The UUID format includes sixteen octets represented as 32 hexadecimal (base 16) digits, displayed in five groups separated by hyphens, in the form 8-4-4-4-12 for a total of 36 characters (32 alphanumeric characters and four hyphens).

Example:

box.cfg{replicaset_uuid='7b853d13-508b-4b8e-82e6-806f088ea6e9'}

Type: string

Default: null

Dynamic: no

instance_uuid

Since version 1.9.0. For replication administration purposes, it is possible to set the universally unique identifiers of the instance (instance_uuid) and the replica set (replicaset_uuid), instead of having the system generate the values.

See the description of replicaset_uuid parameter for details.

Example:

box.cfg{instance_uuid='037fec43-18a9-4e12-a684-a42b716fcd02'}

Type: string

Default: null

Dynamic: no

Networking

• io_collect_interval,
• net_msg_max
• readahead,

io_collect_interval

Since version 1.4.9. The instance will sleep for io_collect_interval seconds between iterations of the event loop. Can be used to reduce CPU load in deployments in which the number of client connections is large, but requests are not so frequent (for example, each connection issues just a handful of requests per second).

Type: float

Default: null

Dynamic: yes

net_msg_max

Since version 1.10.1. To handle messages, Tarantool allocates fibers. To prevent fiber overhead from affecting the whole system, Tarantool restricts how many messages the fibers handle, so that some pending requests are blocked.

On powerful systems, increase net_msg_max and the scheduler will immediately start processing pending requests.

On weaker systems, decrease net_msg_max and the overhead may decrease although this may take some time because the scheduler must wait until already-running requests finish.

When net_msg_max is reached, Tarantool suspends processing of incoming packages until it has processed earlier messages. This is not a direct restriction of the number of fibers that handle network messages, rather it is a system-wide restriction of channel bandwidth. This in turn causes restriction of the number of incoming network messages that the transaction processor thread handles, and therefore indirectly affects the fibers that handle network messages. (The number of fibers is smaller than the number of messages because messages can be released as soon as they are delivered, while incoming requests might not be processed until some time after delivery.)

On typical systems, the default value (768) is correct.

Type: integer

Default: 768

Dynamic: yes

readahead

Since version 1.6.2. The size of the read-ahead buffer associated with a client connection. The larger the buffer, the more memory an active connection consumes and the more requests can be read from the operating system buffer in a single system call. The rule of thumb is to make sure the buffer can contain at least a few dozen requests. Therefore, if a typical tuple in a request is large, e.g. a few kilobytes or even megabytes, the read-ahead buffer size should be increased. If batched request processing is not used, it’s prudent to leave this setting at its default.

Type: integer

Default: 16320

Dynamic: yes

Logging

• log_level
• log
• log_nonblock
• too_long_threshold
• log_format

log_level

Since version 1.6.2. What level of detail the log will have. There are seven levels:

• 1 – SYSERROR
• 2 – ERROR
• 3 – CRITICAL
• 4 – WARNING
• 5 – INFO
• 6 – VERBOSE
• 7 – DEBUG

By setting log_level, one can enable logging of all classes below or equal to the given level. Tarantool prints its logs to the standard error stream by default, but this can be changed with the log configuration parameter.

Type: integer

Default: 5

Dynamic: yes

Warning: prior to Tarantool 1.7.5 there were only six levels and DEBUG was level 6. Starting with Tarantool 1.7.5 VERBOSE is level 6 and DEBUG is level 7. VERBOSE is a new level for monitoring repetitive events which would cause too much log writing if INFO were used instead.

log

Since version 1.7.4. By default, Tarantool sends the log to the standard error stream (stderr). If log is specified, Tarantool sends the log to a file, or to a pipe, or to the system logger.

Example setting for sending the log to a file:

box.cfg{log = 'tarantool.log'}
-- or
box.cfg{log = 'file:tarantool.log'}

This will open the file tarantool.log for output on the server’s default directory. If the log string has no prefix or has the prefix “file:”, then the string is interpreted as a file path.

Example setting for sending the log to a pipe:

box.cfg{log = '| cronolog tarantool.log'}
-- or
box.cfg{log = 'pipe: cronolog tarantool.log'}'

This will start the program cronolog when the server starts, and will send all log messages to the standard input (stdin) of cronolog. If the log string begins with ‘|’ or has the prefix “pipe:”, then the string is interpreted as a Unix pipeline.

Example setting for sending the log to syslog:

box.cfg{log = 'syslog:identity=tarantool'}
-- or
box.cfg{log = 'syslog:facility=user'}
-- or
box.cfg{log = 'syslog:identity=tarantool,facility=user'}
-- or
box.cfg{log = 'syslog:server=unix:/dev/log'}

If the log string begins with “syslog:”, then it is interpreted as a message for the syslogd program which normally is running in the background of any Unix-like platform. The setting can be ‘syslog:’, ‘syslog:facility=…’, ‘syslog:identity=…’, ‘syslog:server=…’, or a combination.

The syslog:identity setting is an arbitrary string which will be placed at the beginning of all messages. The default value is: tarantool.

The syslog:facility setting is currently ignored but will be used in the future. The value must be one of the syslog keywords, which tell syslogd where the message should go. The possible values are: auth, authpriv, cron, daemon, ftp, kern, lpr, mail, news, security, syslog, user, uucp, local0, local1, local2, local3, local4, local5, local6, local7. The default value is: user.

The syslog:server setting is the locator for the syslog server. It can be a Unix socket path beginning with “unix:”, or an ipv4 port number. The default socket value is: dev/log (on Linux) or /var/run/syslog (on Mac OS). The default port value is: 514, the UDP port.

When logging to a file, Tarantool reopens the log on SIGHUP. When log is a program, its pid is saved in the log.logger_pid variable. You need to send it a signal to rotate logs.

Type: string

Default: null

Dynamic: no

log_nonblock

Since version 1.7.4. If log_nonblock equals true, Tarantool does not block on the log file descriptor when it’s not ready for write, and drops the message instead. If log_level is high, and many messages go to the log file, setting log_nonblock to true may improve logging performance at the cost of some log messages getting lost.

This parameter has effect only if the output is going to syslog or to a pipe.

Type: boolean

Default: true

Dynamic: no

too_long_threshold

Since version 1.6.2. If processing a request takes longer than the given value (in seconds), warn about it in the log. Has effect only if log_level is more than or equal to 4 (WARNING).

Type: float

Default: 0.5

Dynamic: yes

log_format

Since version 1.7.6. Log entries have two possible formats:

• ‘plain’ (the default), or
• ‘json’ (with more detail and with JSON labels).

Here is what a log entry looks like after box.cfg{log_format='plain'}:

2017-10-16 11:36:01.508 [18081] main/101/interactive I> set 'log_format' configuration option to "plain"

Here is what a log entry looks like after box.cfg{log_format='json'}:

{"time": "2017-10-16T11:36:17.996-0600",
"level": "INFO",
"message": "set 'log_format' configuration option to \"json\"",
"pid": 18081,|
"cord_name": "main",
"fiber_id": 101,
"fiber_name": "interactive",
"file": "builtin\/box\/load_cfg.lua",
"line": 317}

The log_format='plain' entry has time, process id, cord name, fiber_id, fiber_name, log level, and message.

The log_format='json' entry has the same things along with their labels, and in addition has the file name and line number of the Tarantool source.

Type: string

Default: ‘plain’

Dynamic: yes

box.cfg{log='Log_file'}
log = require('log')
log.info('Log Line #1')

mv Log_file Log_file.bak

log.info('Log Line #2')

ps -A | grep tarantool

kill -HUP process_id

log.info('Log Line #3')

2015-11-30 15:13:06.373 [27469] main/101/interactive I> Log Line #1`
2015-11-30 15:14:25.973 [27469] main/101/interactive I> Log Line #2`

log file has been reopened
2015-11-30 15:15:32.629 [27469] main/101/interactive I> Log Line #3

Feedback

• feedback_enabled
• feedback_host
• feedback_interval

By default a Tarantool daemon sends a small packet once per hour, to https://feedback.tarantool.io. The packet contains three values from box.info: box.info.version, box.info.uuid, and box.info.cluster_uuid. By changing the feedback configuration parameters, users can adjust or turn off this feature.

feedback_enabled

Since version 1.10.1. Whether to send feedback.

If this is set to true, feedback will be sent as described above. If this is set to false, no feedback will be sent.

Type: boolean

Default: true

Dynamic: yes

feedback_host

Since version 1.10.1. The address to which the packet is sent. Usually the recipient is Tarantool, but it can be any URL.

Type: string

Default: ‘https://feedback.tarantool.io’

Dynamic: yes

feedback_interval

Since version 1.10.1. The number of seconds between sendings, usually 3600 (1 hour).

Type: float

Default: 3600

Dynamic: yes

Deprecated parameters

These parameters are deprecated since Tarantool version 1.7.4:

• coredump
• logger
• logger_nonblock
• panic_on_snap_error,
• panic_on_wal_error
• replication_source
• slab_alloc_arena
• slab_alloc_factor
• slab_alloc_maximal
• slab_alloc_minimal
• snap_dir
• snapshot_count
• snapshot_period

coredump

Deprecated, do not use.

Type: boolean

Default: false

Dynamic: no

logger

Deprecated in favor of log. The parameter was only renamed, while the type, values and semantics remained intact.

logger_nonblock

Deprecated in favor of log_nonblock. The parameter was only renamed, while the type, values and semantics remained intact.

panic_on_snap_error

Deprecated in favor of force_recovery.

If there is an error while reading a snapshot file (at server instance start), abort.

Type: boolean

Default: true

Dynamic: no

panic_on_wal_error

Deprecated in favor of force_recovery.

Type: boolean

Default: true

Dynamic: yes

replication_source

Deprecated in favor of replication. The parameter was only renamed, while the type, values and semantics remained intact.

slab_alloc_arena

Deprecated in favor of memtx_memory.

How much memory Tarantool allocates to actually store tuples, in gigabytes. When the limit is reached, INSERT or UPDATE requests begin failing with error ER_MEMORY_ISSUE. While the server does not go beyond the defined limit to allocate tuples, there is additional memory used to store indexes and connection information. Depending on actual configuration and workload, Tarantool can consume up to 20% more than the limit set here.

Type: float

Default: 1.0

Dynamic: no

slab_alloc_factor

Deprecated, do not use.

The multiplier for computing the sizes of memory chunks that tuples are stored in. A lower value may result in less wasted memory depending on the total amount of memory available and the distribution of item sizes.

Type: float

Default: 1.1

Dynamic: no

slab_alloc_maximal

Deprecated in favor of memtx_max_tuple_size. The parameter was only renamed, while the type, values and semantics remained intact.

slab_alloc_minimal

Deprecated in favor of memtx_min_tuple_size. The parameter was only renamed, while the type, values and semantics remained intact.

snap_dir

Deprecated in favor of memtx_dir. The parameter was only renamed, while the type, values and semantics remained intact.

snapshot_period

Deprecated in favor of checkpoint_interval. The parameter was only renamed, while the type, values and semantics remained intact.

snapshot_count

Deprecated in favor of checkpoint_count. The parameter was only renamed, while the type, values and semantics remained intact.