AIS configuration comprises:

Name Scope Comment
ClusterConfig Global Named sections containing name-value knobs
LocalConfig Local Allows to override global defaults on a per-node basis

Cluster-wide (global) configuration is protected, namely: checksummed, versioned, and safely replicated. In effect, global config defines cluster-wide defaults inherited by each node joining the cluster.

Local config includes:

  1. node’s own hostnames (or IP addresses) and mountpaths (data drives);
  2. optionally, names-and-values that were changed for this specific node. For each node in the cluster, the corresponding capability (dubbed config-override) boils down to:
    • inheriting cluster configuration, and optionally
    • optionally, locally overriding assorted inherited defaults (see usage examples below).

Majority of the configuration knobs can be changed at runtime (and at any time). A few read-only variables are explicitly marked in the source; any attempt to modify those at runtime will return “read-only” error message.


For AIStore configuration management using AIS CLI, please see:

The document also contains brief theory of operation and many usage examples.

Configuring for production

Configuring AIS cluster for production requires a careful consideration. First and foremost, there are assorted performance related recommendations.

Optimal performance settings will always depend on your (hardware, network) environment. Speaking of networking, AIS supports 3 (three) logical networks and will, therefore, benefit, performance-wise, if provisioned with up to 3 isolated physical networks or VLANs. The logical networks are:

  • user (aka public)
  • intra-cluster control
  • intra-cluster data

with the corresponding JSON names, respectively:

  • hostname
  • hostname_intra_control
  • hostname_intra_data


  • For Kubernetes deployment, please refer to a separate ais-k8s repository that also contains AIS/K8s Operator and its configuration-defining resources.
  • To configure an optional AIStore authentication server, run $ AIS_AUTHN_ENABLED=true make deploy. For information on AuthN server, please see AuthN documentation.
  • AIS CLI is an easy-to-use convenient command-line management/monitoring tool. To get started with CLI, run make cli (that generates ais executable) and follow the prompts.

Cluster and Node Configuration

The first thing to keep in mind is that there are 3 (three) separate, and separately maintained, pieces:

  1. Cluster configuration that comprises global defaults
  2. Node (local) configuration
  3. Node’s local overrides of global defaults


Cluster Config

To show and/or change global config, simply type one of:

# 1. show cluster config
$ ais show cluster config

# 2. show cluster config in JSON format
$ ais show cluster config --json

# 3. show cluster-wide defaults for all variables prefixed with "time"
$ ais show config cluster time
# or, same:
$ ais show cluster config time
PROPERTY                         VALUE
timeout.cplane_operation         2s
timeout.max_keepalive            4s
timeout.max_host_busy            20s
timeout.startup_time             1m
timeout.send_file_time           5m
timeout.transport_idle_term      4s

# 4. for all nodes in the cluster set startup timeout to 2 minutes
$ ais config cluster timeout.startup_time=2m
config successfully updated

Typically, when we deploy a new AIS cluster, we use configuration template that contains all the defaults - see, for example, JSON template. Configuration sections in this template, and the knobs within those sections, must be self-explanatory, and the majority of those, except maybe just a few, have pre-assigned default values.

Node configuration

As stated above, each node in the cluster inherits global configuration with the capability to override the latter locally.

There are also node-specific settings, such as:

  • log directories
  • network configuration, including node’s hostname(s) or IP addresses
  • node’s mountpaths

Since AIS supports n-way mirroring and erasure coding, we typically recommend not using LVMs and hardware RAIDs.

Example: show node’s configuration

# ais show config t[CCDpt8088]
PROPERTY                                 VALUE                                                           DEFAULT
auth.enabled                             false                                                           -
auth.secret                              aBitLongSecretKey                                               -
backend.conf                             map[aws:map[] gcp:map[]]                                        -
checksum.enable_read_range               false                                                           -
checksum.type                            xxhash                                                          -
checksum.validate_cold_get               true                                                            -
checksum.validate_obj_move               false                                                           -
checksum.validate_warm_get               false                                                           -
(Hint: use `--type` to select the node config's type to show: 'cluster', 'local', 'all'.)

Example: same as above in JSON format:

$ ais show config CCDpt8088 --json | tail -20
    "lastupdate_time": "2021-03-20 18:00:20.393881867 -0700 PDT m=+2907.143584987",
    "uuid": "ZzCknLkMi",
    "config_version": "3",
    "confdir": "/ais",
    "log_dir": "/tmp/ais/log",
    "host_net": {
        "hostname": "",
        "hostname_intra_control": "",
        "hostname_intra_data": "",
        "port": "51081",
        "port_intra_control": "51082",
        "port_intra_data": "51083"
    "fspaths": {"/ais/mp1":{},"/ais/mp2":{},"/ais/mp3":{},"/ais/mp4":{}},
    "test_fspaths": {
        "root": "/tmp/ais",
        "count": 0,
        "instance": 0

Example: use --type option to show only local config

# ais show config koLAt8081 --type local
PROPERTY                         VALUE
confdir                          /ais
log_dir                          /tmp/ais/log
host_net.port                    51081
host_net.port_intra_control      51082
host_net.port_intra_data         51083
fspaths.paths                    /ais/mp1,/ais/mp2,/ais/mp3,/ais/mp4
test_fspaths.root                /tmp/ais
test_fspaths.count               0
test_fspaths.instance            0

Local override (of global defaults)


$ ais show config t[CCDpt8088] timeout
# or, same:
$ ais config node t[CCDpt8088] timeout

PROPERTY                         VALUE   DEFAULT
timeout.cplane_operation         2s      -
timeout.join_startup_time        3m      -
timeout.max_host_busy            20s     -
timeout.max_keepalive            4s      -
timeout.send_file_time           5m      -
timeout.startup_time             1m      -

$ ais config node t[CCDpt8088] timeout.startup_time=90s
config for node "CCDpt8088" successfully updated

$ ais config node t[CCDpt8088] timeout

PROPERTY                         VALUE   DEFAULT
timeout.cplane_operation         2s      -
timeout.join_startup_time        3m      -
timeout.max_host_busy            20s     -
timeout.max_keepalive            4s      -
timeout.send_file_time           5m      -
timeout.startup_time             1m30s   1m

In the DEFAULT column above hyphen (-) indicates that the corresponding value is inherited and, as far as the node CCDpt8088, remains unchanged.

Rest of this document is structured as follows

The picture illustrates one section of the configuration template that, in part, includes listening port:

Configuration: TCP port and URL

Further, test_fspaths section (see below) corresponds to a single local filesystem being partitioned between both local and Cloud buckets. In other words, the test_fspaths configuration option is intended strictly for development.

Configuration: local filesystems

In production, we use an alternative configuration called fspaths: the section of the config that includes a number of local directories, whereby each directory is based on a different local filesystem.

For fspath and mountpath terminology and details, please see section Managing Mountpaths in this document.

An example of 12 fspaths (and 12 local filesystems) follows below:

Example: 12 fspaths


First, some basic facts:

  • AIS cluster is a collection of nodes - members of the cluster.
  • A node can be an AIS proxy (aka gateway) or an AIS target.
  • In either case, HTTP request to read (get) or write (set) specific node’s configuration will have /v1/daemon in its URL path.
  • The capability to carry out cluster-wide configuration updates is also supported. The corresponding HTTP URL will have /v1/cluster in its path.

Both daemon and cluster are the two RESTful resource abstractions supported by the API. Please see AIS API for naming conventions, RESTful resources, as well as API reference and details.

  • To get the node’s up-to-date configuration, execute:
    $ ais show config <daemon-ID>

    This will display all configuration sections and all the named knobs - i.e., configuration variables and their current values.

Most configuration options can be updated either on an individual (target or proxy) daemon, or the entire cluster. Some configurations are “overridable” and can be configured on a per-daemon basis. Some of these are shown in the table below.

For examples and alternative ways to format configuration-updating requests, please see the examples below.

Following is a table-summary that contains a subset of all settable knobs:

NOTE (May 2022): this table is somewhat outdated and must be revisited.

Option name Overridable Default value Description
ec.data_slices No 2 Represents the number of fragments an object is broken into (in the range [2, 100])
ec.disk_only No false If true, EC uses local drives for all operations. If false, EC automatically chooses between memory and local drives depending on the current memory load
ec.enabled No false Enables or disables data protection
ec.objsize_limit No 262144 Indicated the minimum size of an object in bytes that is erasure encoded. Smaller objects are replicated
ec.parity_slices No 2 Represents the number of redundant fragments to provide protection from failures (in the range [2, 32])
ec.compression No "never" LZ4 compression parameters used when EC sends its fragments and replicas over network. Values: “never” - disables, “always” - compress all data, or a set of rules for LZ4, e.g “ratio=1.2” means enable compression from the start but disable when average compression ratio drops below 1.2 to save CPU resources
mirror.burst_buffer No 512 the maximum queue size for the (pending) objects to be mirrored. When exceeded, target logs a warning.
mirror.copies No 1 the number of local copies of an object
mirror.enabled No false If true, for every object PUT a target creates object replica on another mountpath. Later, on object GET request, loadbalancer chooses a mountpath with lowest disk utilization and reads the object from it
rebalance.dest_retry_time No 2m If a target does not respond within this interval while rebalance is running the target is excluded from rebalance process
rebalance.enabled No true Enables and disables automatic rebalance after a target receives the updated cluster map. If the (automated rebalancing) option is disabled, you can still use the REST API (PUT {"action": "start", "value": {"kind": "rebalance"}} v1/cluster) to initiate cluster-wide rebalancing
rebalance.multiplier No 4 A tunable that can be adjusted to optimize cluster rebalancing time (advanced usage only)
transport.quiescent No 20s Rebalance moves to the next stage or starts the next batch of objects when no objects are received during this time interval
versioning.enabled No true Enables and disables versioning. For the supported 3rd party backends, versioning is on only when it enabled for (and supported by) the specific backend
versioning.validate_warm_get No false If false, a target returns a requested object immediately if it is cached. If true, a target fetches object’s version(via HEAD request) from Cloud and if the received version mismatches locally cached one, the target redownloads the object and then returns it to a client
checksum.enable_read_range Yes false See Supported Checksums and Brief Theory of Operations
checksum.type Yes xxhash Checksum type. Please see Supported Checksums and Brief Theory of Operations
checksum.validate_cold_get Yes true Please see Supported Checksums and Brief Theory of Operations
checksum.validate_warm_get Yes false See Supported Checksums and Brief Theory of Operations
client.client_long_timeout Yes 30m Default long client timeout
client.client_timeout Yes 10s Default client timeout
client.list_timeout Yes 2m Client list objects timeout
transport.block_size Yes 262144 Maximum data block size used by LZ4, greater values may increase compression ration but requires more memory. Value is one of 64KB, 256KB(AIS default), 1MB, and 4MB
disk.disk_util_high_wm Yes 80 Operations that implement self-throttling mechanism, e.g. LRU, turn on the maximum throttle if disk utilization is higher than disk_util_high_wm
disk.disk_util_low_wm Yes 60 Operations that implement self-throttling mechanism, e.g. LRU, do not throttle themselves if disk utilization is below disk_util_low_wm
disk.iostat_time_long Yes 2s The interval that disk utilization is checked when disk utilization is below disk_util_low_wm.
disk.iostat_time_short Yes 100ms Used instead of iostat_time_long when disk utilization reaches disk_util_high_wm. If disk utilization is between disk_util_high_wm and disk_util_low_wm, a proportional value between iostat_time_short and iostat_time_long is used.
distributed_sort.call_timeout Yes "10m" a maximum time a target waits for another target to respond
distributed_sort.compression Yes "never" LZ4 compression parameters used when dSort sends its shards over network. Values: “never” - disables, “always” - compress all data, or a set of rules for LZ4, e.g “ratio=1.2” means enable compression from the start but disable when average compression ratio drops below 1.2 to save CPU resources
distributed_sort.default_max_mem_usage Yes "80%" a maximum amount of memory used by running dSort. Can be set as a percent of total memory(e.g 80%) or as the number of bytes(e.g, 12G)
distributed_sort.dsorter_mem_threshold Yes "100GB" minimum free memory threshold which will activate specialized dsorter type which uses memory in creation phase - benchmarks shows that this type of dsorter behaves better than general type
distributed_sort.duplicated_records Yes "ignore" what to do when duplicated records are found: “ignore” - ignore and continue, “warn” - notify a user and continue, “abort” - abort dSort operation
distributed_sort.ekm_malformed_line Yes "abort" what to do when extraction key map notices a malformed line: “ignore” - ignore and continue, “warn” - notify a user and continue, “abort” - abort dSort operation
distributed_sort.ekm_missing_key Yes "abort" what to do when extraction key map have a missing key: “ignore” - ignore and continue, “warn” - notify a user and continue, “abort” - abort dSort operation
distributed_sort.missing_shards Yes "ignore" what to do when missing shards are detected: “ignore” - ignore and continue, “warn” - notify a user and continue, “abort” - abort dSort operation
fshc.enabled Yes true Enables and disables filesystem health checker (FSHC)
log.level Yes 3 Set global logging level. The greater number the more verbose log output
lru.capacity_upd_time Yes 10m Determines how often AIStore updates filesystem usage
lru.dont_evict_time Yes 120m LRU does not evict an object which was accessed less than dont_evict_time ago
lru.enabled Yes true Enables and disabled the LRU
space.highwm Yes 90 LRU starts immediately if a filesystem usage exceeds the value
space.lowwm Yes 75 If filesystem usage exceeds highwm LRU tries to evict objects so the filesystem usage drops to lowwm
periodic.notif_time Yes 30s An interval of time to notify subscribers (IC members) of the status and statistics of a given asynchronous operation (such as Download, Copy Bucket, etc.)
periodic.stats_time Yes 10s A housekeeping time interval to periodically update and log internal statistics, remove/rotate old logs, check available space (and run LRU xaction if need be), etc.
resilver.enabled Yes true Enables and disables automatic reresilver after a mountpath has been added or removed. If the (automated resilvering) option is disabled, you can still use the REST API (PUT {"action": "start", "value": {"kind": "resilver", "node": targetID}} v1/cluster) to initiate resilvering
timeout.max_host_busy Yes 20s Maximum latency of control-plane operations that may involve receiving new bucket metadata and associated processing
timeout.send_file_time Yes 5m Timeout for sending/receiving an object from another target in the same cluster
timeout.transport_idle_term Yes 4s Max idle time to temporarily teardown long-lived intra-cluster connection

Startup override

AIS command-line allows to override configuration at AIS node’s startup. For example:

$ aisnode -config=/etc/ais.json -local_config=/etc/ais_local.json -role=target -config_custom="client.timeout=13s,log.level=4"

As shown above, the CLI option in-question is: confjson. Its value is a JSON-formatted map of string names and string values. By default, the config provided in config_custom will be persisted on the disk. To make it transient either add -transient=true flag or add additional JSON entry:

$ aisnode -config=/etc/ais.json -local_config=/etc/ais_local.json -role=target -transient=true -config_custom="client.timeout=13s, transient=true"

Another example. To override locally-configured address of the primary proxy, run:

$ aisnode -config=/etc/ais.json -local_config=/etc/ais_local.json -role=target -config_custom="proxy.primary_url=http://G"
# where G denotes the designated primary's hostname and port.

To achieve the same on temporary basis, add -transient=true as follows:

$ aisnode -config=/etc/ais.json -local_config=/etc/ais_local.json -role=target -config_custom="proxy.primary_url=http://G"

Please see AIS command-line for other command-line options and details.

Managing mountpaths

  • Mountpath - is a single disk or a volume (a RAID) formatted with a local filesystem of choice, and a local directory that AIS can fully own and utilize (to store user data and system metadata). Note that any given disk (or RAID) can have (at most) one mountpath (meaning no disk sharing) and mountpath directories cannot be nested. Further:
    • a mountpath can be temporarily disabled and (re)enabled;
    • a mountpath can also be detached and (re)attached, thus effectively supporting growth and “shrinkage” of local capacity;
    • it is safe to execute the 4 listed operations (enable, disable, attach, detach) at any point during runtime;
    • in a typical deployment, the total number of mountpaths would compute as a direct product of (number of storage targets) x (number of disks in each target).

Configuration option fspaths specifies the list of local mountpath directories. Each configured fspath is, simply, a local directory that provides the basis for AIS mountpath.

In regards non-sharing of disks between mountpaths: for development we make an exception, such that multiple mountpaths are actually allowed to share a disk and coexist within a single filesystem. This is done strictly for development convenience, though.

AIStore REST API makes it possible to list, add, remove, enable, and disable a fspath (and, therefore, the corresponding local filesystem) at runtime. Filesystem’s health checker (FSHC) monitors the health of all local filesystems: a filesystem that “accumulates” I/O errors will be disabled and taken out, as far as the AIStore built-in mechanism of object distribution. For further details about FSHC, please refer to FSHC readme.

Disabling extended attributes

To make sure that AIStore does not utilize xattrs, configure:

  • checksum.type=none
  • versioning.enabled=true, and

for all targets in AIStore cluster.

Or, simply update global configuration (to have those cluster-wide defaults later inherited by all newly created buckets).

This can be done via the common configuration “part” that’d be further used to deploy the cluster.

Extended attributes can be disabled on per bucket basis. To do this, turn off saving metadata to disks (CLI):

$ ais bucket props ais://mybucket
Bucket props successfully updated
"" set to: "never" (was: "")

Disable extended attributes only if you need fast and temporary storage. Without xattrs, a node loses its objects after the node reboots. If extended attributes are disabled globally when deploying a cluster, node IDs are not permanent and a node can change its ID after it restarts.

Enabling HTTPS

To switch from HTTP protocol to an encrypted HTTPS, configure net.http.use_https=true and modify net.http.server_crt and net.http.server_key values so they point to your OpenSSL certificate and key files respectively (see AIStore configuration).

Filesystem Health Checker

Default installation enables filesystem health checker component called FSHC. FSHC can be also disabled via section “fshc” of the configuration.

When enabled, FSHC gets notified on every I/O error upon which it performs extensive checks on the corresponding local filesystem. One possible outcome of this health-checking process is that FSHC disables the faulty filesystems leaving the target with one filesystem less to distribute incoming data.

Please see FSHC readme for further details.


In addition to user-accessible public network, AIStore will optionally make use of the two other networks: internal (or intra-cluster) and replication. If configured via the net section of the configuration, the intra-cluster network is utilized for latency-sensitive control plane communications including keep-alive and metasync. The replication network is used, as the name implies, for a variety of replication workloads.

All the 3 (three) networking options are enumerated here.

Reverse proxy

AIStore gateway can act as a reverse proxy vis-à-vis AIStore storage targets. This functionality is limited to GET requests only and must be used with caution and consideration. Related configuration variable is called rproxy - see sub-section http of the section net. For further details, please refer to this readme.

Curl examples

The following assumes that G and T are the (hostname:port) of one of the deployed gateways (in a given AIS cluster) and one of the targets, respectively.

Cluster-wide operation (all nodes)

  • Set the stats logging interval to 1 second
$ curl -i -X PUT -H 'Content-Type: application/json' -d '{"action": "set-config","name": "periodic.stats_time", "value": "1s"}' 'http://G/v1/cluster'

or, same:

$ curl -i -X PUT 'http://G/v1/cluster/set-config?periodic.stats_time=1s'

Notice the two alternative ways to form the requests.

Cluster-wide operation (all nodes)

  • Set the stats logging interval to 2 minutes
$ curl -i -X PUT -H 'Content-Type: application/json' -d '{"action": "set-config","name": "periodic.stats_time", "value": "2m"}' 'http://G/v1/cluster'

Cluster-wide operation (all nodes)

  • Set the default number of n-way copies to 4 (can still be redefined on a per-bucket basis)
$ curl -i -X PUT -H 'Content-Type: application/json' -d '{"action": "set-config","name": "mirror.copies", "value": "4"}' 'http://G/v1/cluster'

# or, same using CLI:
$ ais config cluster mirror.copies 4

Single-node operation (single node)

  • Set log level = 1
$ curl -i -X PUT -H 'Content-Type: application/json' -d '{"action": "set-config","name": "log.level", "value": "1"}' 'http://T/v1/daemon'
# or, same:
$ curl -i -X PUT 'http://T/v1/daemon/set-config?log.level=1'

# or, same using CLI (assuming the node in question is t[tZktGpbM]):
$ ais config node t[tZktGpbM] log.level 1

CLI examples

AIS CLI is an integrated management-and-monitoring command line tool. The following CLI command sequence, first - finds out all AIS knobs that contain substring “time” in their names, second - modifies list_timeout from 2 minutes to 5 minutes, and finally, displays the modified value:

$ ais show config p[rZTp8080] --type all --json | jq '.timeout.list_timeout'

$ ais config cluster timeout.list_timeout=5m
Config has been updated successfully.

$ ais show config p[rZTp8080] --type all --json | jq '.timeout.list_timeout'

The example above demonstrates cluster-wide configuration update but note: single-node updates are also supported.

Cluster-wide operation (all nodes)

  • Set periodic.stats_time = 1 minute, periodic.iostat_time_long = 4 seconds
$ ais config cluster periodic.stats_time=1m disk.iostat_time_long=4s

Single-node operation (single node)

AIS configuration includes a section called disk. The disk in turn contains several knobs - one of those knobs is disk.iostat_time_long, another - disk.disk_util_low_wm. To update one or both of those named variables on all or one of the clustered nodes, you could:

  • Set disk.iostat_time_long = 3 seconds, disk.disk_util_low_wm = 40 percent on daemon with ID target1
$ ais config node target1 periodic.stats_time=1m disk.iostat_time_long=4s