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Administration Guide

docs/operating-scylla/admin.rst

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========================= Administration Guide

For training material, also check out the Admin Procedures lesson <https://university.scylladb.com/courses/scylla-operations/lessons/admin-procedures-and-basic-monitoring/>_ on ScyllaDB University.

System Requirements

Make sure you have met the :doc:System Requirements </getting-started/system-requirements> before you install and configure ScyllaDB.

Download and Install

See the :doc:getting started page </getting-started/index> for info on installing ScyllaDB on your platform.

System Configuration

See :ref:System Configuration Guide for details on optimum OS settings for ScyllaDB. (These settings are performed automatically in the ScyllaDB packages, Docker containers, and Amazon AMIs.)

.. _admin-scylla-configuration:

ScyllaDB Configuration

ScyllaDB configuration files are:

+-------------------------------------------------------+-----------------------------------+ | Installed location | Description | +=======================================================+===================================+ | :code:/etc/default/scylla-server (Ubuntu/Debian) | Server startup options | | :code:/etc/sysconfig/scylla-server (others) | | +-------------------------------------------------------+-----------------------------------+ | :code:/etc/scylla/scylla.yaml | Main ScyllaDB configuration file | +-------------------------------------------------------+-----------------------------------+ | :code:/etc/scylla/cassandra-rackdc.properties | Rack & dc configuration file | +-------------------------------------------------------+-----------------------------------+

.. _check-your-current-version-of-scylla:

Check your current version of ScyllaDB

This command allows you to check your current version of ScyllaDB. Note that this command is not the :doc:nodetool version </operating-scylla/nodetool-commands/version> command which reports the CQL version. If you are looking for the CQL or Cassandra version, refer to the CQLSH reference for :ref:SHOW VERSION <cqlsh-show-version>.

.. code-block:: shell

scylla --version

Output displays the ScyllaDB version. Your results may differ.

.. code-block:: shell

4.4.0-0.20210331.05c6a40f0

.. _admin-address-configuration-in-scylla:

Address Configuration in ScyllaDB

The following addresses can be configured in scylla.yaml:

.. list-table:: :widths: 30 70 :header-rows: 1

    • Address Type
    • Description
    • listen_address
    • Address ScyllaDB listens for connections from other nodes. See storage_port and ssl_storage_ports.
    • rpc_address
    • Address on which ScyllaDB is going to expect CQL client connections. See rpc_port, native_transport_port and native_transport_port_ssl in the :ref:Networking <cqlsh-networking> parameters.
    • broadcast_address
    • Address that is broadcasted to tell other ScyllaDB nodes to connect to. Related to listen_address above.
    • broadcast_rpc_address
    • Address that is broadcasted to tell the clients to connect to. Related to rpc_address.
    • seeds
    • The broadcast_addresses of the existing nodes. You must specify the address of at least one existing node.
    • endpoint_snitch
    • Node's address resolution helper.
    • api_address
    • Address for REST API requests. See api_port in the :ref:Networking <cqlsh-networking> parameters.
    • prometheus_address
    • Address for Prometheus queries. See prometheus_port in the :ref:Networking <cqlsh-networking> parameters and ScyllaDB Monitoring Stack <https://monitoring.docs.scylladb.com/stable/>_ for more details.
    • replace_node_first_boot
    • Host ID of a dead node this ScyllaDB node is replacing. Refer to :doc:Replace a Dead Node in a ScyllaDB Cluster </operating-scylla/procedures/cluster-management/replace-dead-node> for more details.

.. note:: When the listen_address, rpc_address, broadcast_address, and broadcast_rpc_address parameters are not set correctly, ScyllaDB does not work as expected.

scylla-server

The :code:scylla-server file contains configuration related to starting up the ScyllaDB server.

.. _admin-scylla.yaml:

.. include:: /operating-scylla/scylla-yaml.inc

.. _object-storage-configuration:

Configuring Object Storage

ScyllaDB can communicate directly with S3-compatible object storage. Before using features that rely on object storage, you must first enable and configure access to the storage endpoints.

Storage endpoints define where data can be stored and are specified in the scylla.yaml configuration file. The relevant section of scylla.yaml should follow this format:

.. code-block:: yaml

object_storage_endpoints: - name: http[s]://<endpoint_address_or_domain_name>[:<port_number>] aws_region: <region_name> # optional, e.g. us-east-1 iam_role_arn: <iam_role> # optional

Example:

.. code:: yaml

object_storage_endpoints: - name: https://s3.us-east-1.amazonaws.com aws_region: us-east-1 iam_role_arn: arn:aws:iam::123456789012:instance-profile/my-instance-instance-profile

The aws_region option can also be specified using the AWS_DEFAULT_REGION environment variable.

The AWS-related credentials options (aws_access_key_id, aws_secret_access_key, aws_session_token) can be configured using the following environment variables:

  • AWS_ACCESS_KEY_ID
  • AWS_SECRET_ACCESS_KEY
  • AWS_SESSION_TOKEN

The ScyllaDB S3 client will first attempt to access credentials from environment variables. If it fails to obtain credentials, it will then try to retrieve them from the AWS Security Token Service (STS) or the EC2 Instance Metadata Service.

.. note::

  • All AWS-related parameters must be either present or absent as a group.
  • When set, these values are used by the S3 client to sign requests.
  • If not set, requests are sent unsigned, which may not be accepted by all servers.

.. _admin-compression:

Compression

In ScyllaDB, you can configure compression at rest and compression in transit. For compression in transit, you can configure compression between nodes or between the client and the node.

.. _admin-client-node-compression:

Client - Node Compression

Compression between the client and the node is set by the driver that the application is using to access ScyllaDB.

For example:

  • ScyllaDB Python Driver <https://python-driver.docs.scylladb.com/master/api/cassandra/cluster.html#cassandra.cluster.Cluster.compression>_
  • ScyllaDB Java Driver <https://github.com/scylladb/java-driver/tree/3.7.1-scylla/manual/compression>_
  • Go Driver <https://godoc.org/github.com/gocql/gocql#Compressor>_

Refer to ScyllaDB Drivers <https://docs.scylladb.com/stable/drivers/index.html>_ for more drivers.

.. _internode-compression:

Internode Compression

Internode compression is configured in the scylla.yaml

internode_compression controls whether traffic between nodes is compressed.

  • all - all traffic is compressed.
  • dc - traffic between different datacenters is compressed.
  • none - nothing is compressed (default).

Configuring TLS/SSL in scylla.yaml

ScyllaDB supports encryption between nodes and between client and node. See the ScyllaDB :doc:ScyllaDB TLS/SSL guide: </operating-scylla/security/index> for configuration settings.

.. _cqlsh-networking:

Networking

The ScyllaDB ports are detailed in the table below. For ScyllaDB Manager ports, see the ScyllaDB Manager Documentation <https://manager.docs.scylladb.com/>_.

.. image:: /operating-scylla/security/Scylla-Ports2.png

.. include:: /operating-scylla/_common/networking-ports.rst

All ports above need to be open to external clients (CQL) and other nodes (RPC). REST API port can be kept closed for incoming external connections.

Advanced networking

It is possible that a client, or another node, may need to use a different IP address to connect to a ScyllaDB node from the address that the node is listening on. This is the case when a node is behind port forwarding. ScyllaDB allows for setting alternate IP addresses.

Do not set any IP address to :code:0.0.0.0.

.. list-table:: :widths: 30 40 30 :header-rows: 1

    • Address Type
    • Description
    • Default
    • listen_address (required)
    • Address ScyllaDB listens for connections from other nodes. See storage_port and ssl_storage_ports.
    • No default
    • rpc_address (required)
    • Address on which ScyllaDB is going to expect CQL clients connections. See rpc_port, native_transport_port and native_transport_port_ssl in the :ref:Networking <cqlsh-networking> parameters.
    • No default
    • broadcast_address
    • Address that is broadcasted to tell other ScyllaDB nodes to connect to. Related to listen_address above.
    • listen_address
    • broadcast_rpc_address
    • Address that is broadcasted to tell the clients to connect to. Related to rpc_address.
    • rpc_address

If other nodes can connect directly to :code:listen_address, then :code:broadcast_address does not need to be set.

If clients can connect directly to :code:rpc_address, then :code:broadcast_rpc_address does not need to be set.

.. note:: For tips and examples on how to configure these addresses, refer to :doc:How to Properly Set Address Values in scylla.yaml </kb/yaml-address>

.. _admin-core-dumps:

Core dumps

On RHEL and CentOS, the Automatic Bug Reporting Tool <https://abrt.readthedocs.io/en/latest/>_ conflicts with ScyllaDB coredump configuration. Remove it before installing ScyllaDB: :code:sudo yum remove -y abrt

ScyllaDB places any core dumps in :code:var/lib/scylla/coredump. They are not visible with the :code:coredumpctl command. See the :doc:System Configuration Guide </getting-started/system-configuration/> for details on core dump configuration scripts. Check with ScyllaDB support before sharing any core dump, as they may contain sensitive data.

Schedule fstrim

ScyllaDB sets up daily fstrim on the filesystem(s), containing your ScyllaDB commitlog and data directory. This utility will discard, or trim, any blocks no longer in use by the filesystem.

Experimental Features

ScyllaDB uses experimental flags to expose non-production-ready features safely. These features are not stable enough to be used in production, and their API will likely change, breaking backward or forward compatibility.

In recent ScyllaDB versions, these features are controlled by the experimental_features list in scylla.yaml, allowing one to choose which experimental to enable. Use scylla --help to get the list of experimental features.

.. _admin-views-with-tablets:

Views with Tablets

Materialized Views (MV) and Secondary Indexes (SI) are supported in keyspaces that use tablets only when the keyspaces are :term:RF-rack-valid <RF-rack-valid keyspace>.

When a keyspace contains a Materialized View or Secondary Index, some operations are restricted to maintain the RF-rack condition. The following actions are not allowed while the view or index is present:

  • Altering the keyspace's replication factor to a value that would violate the RF-rack-valid property
  • Adding a node in a new rack in an existing datacenter
  • Removing the last node in a rack

Monitoring

ScyllaDB exposes interfaces for online monitoring, as described below.

Monitoring Interfaces

ScyllaDB Monitoring Interfaces <https://monitoring.docs.scylladb.com/stable/reference/monitoring_apis.html>_

Monitoring Stack

|mon_root|

.. REST

.. include:: /operating-scylla/rest.rst

Un-contents

ScyllaDB is designed for high performance before tuning, for fewer layers that interact in unpredictable ways, and to use better algorithms that do not require manual tuning. The following items are found in the manuals for other data stores but do not need to appear here.

Configuration un-contents

  • Generating tokens
  • Configuring virtual nodes

Operations un-contents

  • Tuning Bloom filters
  • Data caching
  • Configuring memtable throughput
  • Configuring compaction
  • Compression

Testing compaction and compression

  • Tuning Java resources
  • Purging gossip state on a node

Help with ScyllaDB

Contact Support <https://www.scylladb.com/product/support/>, or visit the ScyllaDB Community <https://www.scylladb.com/open-source-community/> page for peer support.

.. include:: /rst_include/apache-copyrights-index.rst

.. include:: /rst_include/apache-copyrights-index-all-attributes.rst