Configuration Flags Reference

This page provides a comprehensive reference for configuration flags used across YugabyteDB components. Flags allow you to customize behavior, tune performance, configure security, and manage resources.

Overview

YugabyteDB uses configuration flags (also called gflags) to control various aspects of database operation. Flags can be set for different components:

yb-master - Master server flags for cluster coordination
yb-tserver - Tablet server flags for data storage and processing
yugabyted - Simplified deployment utility flags

Flag Types

YugabyteDB flags are categorized by their runtime behavior:

Flag Type	Description	Restart Required
RUNTIME	Can be changed at runtime using `yb-admin`	No
NON_RUNTIME	Requires server restart to take effect	Yes
AUTO	Auto-promoted flags for rolling upgrades	Varies
UNKNOWN	Stability not yet determined	Potentially
TEST	Used for testing only, not for production	N/A

Setting Flags

Command Line

Set flags directly when starting a server:

./bin/yb-master --replication_factor=3 --fs_data_dirs=/data

Configuration File

Use a flagfile to store all flags:

# master.conf
--replication_factor=3
--fs_data_dirs=/data/master
--master_addresses=10.0.0.1:7100,10.0.0.2:7100,10.0.0.3:7100

Start with the flagfile:

./bin/yb-master --flagfile=/etc/yugabyte/master.conf

Runtime Modification

For RUNTIME flags, use yb-admin:

# Set a runtime flag on yb-tserver
yb-admin -master_addresses <master-addresses> \
  set_flag <tserver-host>:9100 <flag-name> <new-value>

# Example
yb-admin -master_addresses 10.0.0.1:7100 \
  set_flag 10.0.0.1:9100 rocksdb_compact_flush_rate_limit_bytes_per_sec 268435456

YugabyteDB Anywhere

If using YugabyteDB Anywhere, set flags through the Edit Flags feature in the UI.

Common Flag Categories

General Server Configuration

Core Server Flags

--version

flag

Display version and build information, then exit.

--flagfile

string

Path to configuration file containing flags.Example: --flagfile=/etc/yugabyte/master.conf

--max_clock_skew_usec

int64

Maximum expected clock skew between nodes in microseconds.Default: 500000 (500ms)Component: yb-master, yb-tserver

--time_source

string

Time source for the database. Set to clockbound for highly accurate time.Default: ""Valid values: "" (system), clockboundComponent: yb-master, yb-tserver

Networking Flags

--rpc_bind_addresses

string

Comma-separated list of network addresses to bind for RPC.Default: Private IP of hostComponent: yb-master, yb-tserver

--server_broadcast_addresses

string

Public IP or DNS hostname for server-to-server communication.Default: ""Component: yb-master, yb-tserver

--dns_cache_expiration_ms

int32

Duration in milliseconds until cached DNS resolution expires.Default: 60000 (1 minute)Component: yb-master, yb-tserver

--use_private_ip

string

Policy for using private IPs: never, zone, region.Default: neverComponent: yb-master, yb-tserver

Storage Flags

--fs_data_dirs

string

Comma-separated list of directories for data storage.Required: YesComponent: yb-master, yb-tserverExample: /data/disk1,/data/disk2,/data/disk3

--fs_wal_dirs

string

Comma-separated list of directories for write-ahead logs.Default: Same as --fs_data_dirsComponent: yb-master, yb-tserver

--rocksdb_block_cache_size_bytes

int64

Size of RocksDB block cache in bytes. -1 for automatic sizing.Default: -1Component: yb-tserver

--rocksdb_compact_flush_rate_limit_bytes_per_sec

int64

Rate limit for compaction and flush in bytes per second.Default: 256000000 (256 MB/s)Component: yb-tserver

--db_block_size_bytes

int32

Size of RocksDB data blocks in bytes.Default: 32768 (32 KB)Component: yb-tserver

Memory Flags

--memory_limit_hard_bytes

int64

Maximum memory limit in bytes. 0 uses percentage of system RAM.Default: 0Component: yb-master, yb-tserver

--default_memory_limit_to_ram_ratio

double

Percentage of RAM to use when memory_limit_hard_bytes is 0.Default: 0.10 (10%)Component: yb-master, yb-tserver

--use_memory_defaults_optimized_for_ysql

boolean

Optimize memory defaults for YSQL workloads.Default: falseComponent: yb-master, yb-tserver

Logging Flags

--log_dir

string

Directory for log files.Default: Same as --fs_data_dirsComponent: yb-master, yb-tserver

--max_log_size

int32

Maximum log file size in megabytes.Default: 1800 (1.8 GB)Component: yb-master, yb-tserver

--minloglevel

int32

Minimum log level: 0 (INFO), 1 (WARN), 2 (ERROR), 3 (FATAL).Default: 0Component: yb-master, yb-tserver

--logtostderr

boolean

Write logs to stderr instead of files.Default: falseComponent: yb-master, yb-tserver

Cluster Configuration

--master_addresses

string

Comma-separated list of master RPC addresses.Required: Yes (yb-master)Component: yb-masterExample: 10.0.0.1:7100,10.0.0.2:7100,10.0.0.3:7100

--tserver_master_addrs

string

Comma-separated list of master addresses for tablet server.Required: Yes (yb-tserver)Component: yb-tserver

--replication_factor

int32

Number of replicas for each tablet.Default: 3Valid range: 1-7 (odd numbers recommended)Component: yb-master

YSQL Configuration

YSQL Core Flags

--enable_ysql

boolean

Enable YSQL API.Default: trueComponent: yb-master, yb-tserver

--ysql_pg_conf_csv

string

Comma-separated PostgreSQL configuration parameters.Component: yb-tserverExample: max_connections=200,shared_buffers=2GB

--ysql_enable_auth

boolean

Enable YSQL authentication.Default: falseComponent: yb-tserver

--ysql_hba_conf_csv

string

PostgreSQL host-based authentication rules.Component: yb-tserver

YSQL Connection Management

--enable_ysql_conn_mgr

boolean

Enable YSQL connection manager for connection pooling.Default: falseComponent: yb-tserver

--ysql_conn_mgr_port

uint32

Port for YSQL connection manager.Default: 5433Component: yb-tserver

--ysql_conn_mgr_max_pools

int32

Maximum number of connection pools.Default: 10000Component: yb-tserver

Performance Tuning

Compaction Settings

--scheduled_full_compaction_frequency_hours

int32

Frequency in hours for scheduled full compaction. 0 disables.Default: 0Component: yb-tserver

--auto_compact_percent_obsolete

double

Percentage of obsolete keys to trigger automatic compaction.Default: 99Component: yb-tserver

--auto_compact_min_obsolete_keys_found

uint32

Minimum obsolete keys for automatic compaction.Default: 10000Component: yb-tserver

RPC Queue Configuration

--tablet_server_svc_queue_length

int32

Queue size for tablet server reads and writes.Default: 5000Component: yb-tserver

--master_svc_queue_length

int32

RPC queue length for master service.Default: 1000Component: yb-master

Heartbeat Configuration

--heartbeat_interval_ms

int32

Interval between heartbeats to master in milliseconds.Default: 1000Component: yb-tserver

--heartbeat_rpc_timeout_ms

int32

Timeout for heartbeat RPC in milliseconds.Default: 15000Component: yb-tserver

Security

Encryption Flags

--use_client_to_server_encryption

boolean

Enable SSL/TLS for client-to-server communication.Default: falseComponent: yb-master, yb-tserver

--use_node_to_node_encryption

boolean

Enable SSL/TLS for node-to-node communication.Default: falseComponent: yb-master, yb-tserver

--certs_dir

string

Directory containing SSL certificates and keys.Default: ""Component: yb-master, yb-tserver

--allow_insecure_connections

boolean

Allow insecure connections when encryption is enabled.Default: trueComponent: yb-tserver

Web Server Security

--webserver_certificate_file

string

SSL certificate file for web server (.pem format).Default: ""Component: yb-master, yb-tserver

--webserver_password_file

string

.htpasswd file for web server authentication.Default: ""Component: yb-master, yb-tserver

Flag Naming Conventions

YugabyteDB flags follow these naming patterns:

Component prefix: master_*, tserver_*, ysql_*, cql_*
Feature area: *_rpc_*, *_log_*, *_cache_*, *_compaction_*
Units: *_ms (milliseconds), *_bytes, *_mb, *_usec (microseconds)

Best Practices

Production Deployments

Use flagfiles for configuration management
Document all custom flags and their purpose
Test flag changes in staging before production
Monitor impact after flag changes
Version control your flagfiles

Performance Tuning

Start with defaults and measure baseline performance
Change one flag at a time to isolate impact
Monitor metrics before and after changes
Document performance improvements for future reference

Common Flag Configurations

# yb-tserver flags for high-performance workloads
--tablet_server_svc_queue_length=10000
--rocksdb_compact_flush_rate_limit_bytes_per_sec=524288000
--rocksdb_block_cache_size_bytes=10737418240
--memory_limit_hard_bytes=21474836480

Viewing Current Flags

To view all current flag values:

# View yb-master flags
curl http://localhost:7000/varz

# View yb-tserver flags
curl http://localhost:9000/varz

Configuration

System Tables

Configuration Flags Reference

Overview

Flag Types

Setting Flags

Command Line

Configuration File

Runtime Modification

YugabyteDB Anywhere

Common Flag Categories

General Server Configuration

YSQL Configuration

Performance Tuning

Security

Flag Naming Conventions

Best Practices

Production Deployments

Performance Tuning

Common Flag Configurations

Viewing Current Flags

See Also

Build docs developers (and LLMs) love

Configuration

System Tables

​Overview

​Flag Types

​Setting Flags

​Command Line

​Configuration File

​Runtime Modification

​YugabyteDB Anywhere

​Common Flag Categories

​General Server Configuration

​YSQL Configuration

​Performance Tuning

​Security

​Flag Naming Conventions

​Best Practices

​Production Deployments

​Performance Tuning

​Common Flag Configurations

​Viewing Current Flags

​See Also

Build docs developers (and LLMs) love

Overview

Flag Types

Setting Flags

Command Line

Configuration File

Runtime Modification

YugabyteDB Anywhere

Common Flag Categories

General Server Configuration

YSQL Configuration

Performance Tuning

Security

Flag Naming Conventions

Best Practices

Production Deployments

Performance Tuning

Common Flag Configurations

Viewing Current Flags

See Also