ScyllaDB Documentation Logo Documentation
  • Server
    • ScyllaDB Open Source
    • ScyllaDB Enterprise
    • ScyllaDB Alternator
  • Cloud
  • Tools
    • ScyllaDB Manager
    • ScyllaDB Monitoring Stack
    • ScyllaDB Operator
  • Drivers
    • CQL Drivers
    • DynamoDB Drivers
Download
Menu
ScyllaDB Docs ScyllaDB Open Source Knowledge Base Increase Scylla resource limits over systemd

Increase Scylla resource limits over systemd¶

Topic: Increasing resource limits when Scylla runs and is managed via systemd

Audience: Scylla administrators

Issue¶

Updates to /etc/security/limits.d/scylla.conf do not have any effect. After a cluster rolling restart is completed, the Scylla limits listed under /proc/<PID>/limits are still the same or lower than what has been configured.

Root Cause¶

When running under systemd, Scylla enforces the LimitNOFILE and LimitNPROC values under /lib/systemd/system/scylla-server.service, where:

LimitNOFILE - Maximum number of file descriptors allowed to be opened simultaneously (defaults to 800000)

LimitNPROC - Maximum number of processes allowed to run in parallel (defaults to 8096)

Even though Scylla’s provided defaults are suitable for most workloads, there may be situations on which these values may need to be overriden.

Before you start¶

The Linux kernel imposes an upper limit on the maximum number of file-handles that a process may allocate, which takes precedence over systemd. Such limit may be persistently increased by tuning the fs.nr_open parameter in the /etc/sysctl.conf file.

The fs.nr_open parameter default value is 1048576 (1024*1024) and it must be increased whenever it is required to overcome such limit.

As a rule of thumb, always ensure that the value of fs.nr_open is equal or greater than the maximum number of file-handles that Scylla may be able to consume.

  1. To check the value of fs.nr_open run:

sysctl fs.nr_open
fs.nr_open = 1048576
  1. Edit the file /etc/sysctl.conf as root, and increase the value of fs.nr_open:

sudo vi /etc/sysctl.conf
fs.nr_open=5000000
  1. Save the changes and apply the new setting to the running configuration:

sudo sysctl -p

Solution¶

  1. To override Scylla limits on systemd, run:

sudo systemctl edit scylla-server.service
  1. Within the opened text editor, add the following lines and adjust the parameters as needed, e.g.:

Warning: Avoid setting the value of such fields to Infinity as this can lead to unpredictable behaviors. When adjusting the value of LimitNOFILE always set it to a value which is equal or lower than the value of fs.nr_open

[Service]
LimitNOFILE=5000000
  1. Restart Scylla:

sudo systemctl restart scylla-server.service

This will create a configuration file named override.conf under the /etc/systemd/system/scylla-server.service.d folder. Whenever editing this file by hand manually, remember to run sudo systemctl daemon-reload before restarting Scylla, so that systemd reloads the changes.

  1. To check the updated limits allowed by the Scylla process run:

cat /proc/$(pidof scylla)/limits

References¶

  • The Linux Kernel Documentation for /proc/sys/fs/* <https://www.kernel.org/doc/Documentation/sysctl/fs.txt>

  • systemd.exec(5) manpage

PREVIOUS
Scylla and Spark integration
NEXT
Scylla Seed Nodes
ScyllaDB Open Source
  • 5.1
    • master
    • 5.2
    • 5.1
  • Getting Started
    • Install Scylla
      • ScyllaDB Web Installer for Linux
      • Scylla Unified Installer (relocatable executable)
      • Air-gapped Server Installation
      • What is in each RPM
      • Scylla Housekeeping and how to disable it
      • Scylla Developer Mode
      • Scylla Configuration Reference
    • Configure Scylla
    • ScyllaDB Requirements
      • System Requirements
      • OS Support by Platform and Version
      • Scylla in a Shared Environment
    • Migrate to ScyllaDB
      • Migration Process from Cassandra to Scylla
      • Scylla and Apache Cassandra Compatibility
      • Migration Tools Overview
    • Integration Solutions
      • Integrate Scylla with Spark
      • Integrate Scylla with KairosDB
      • Integrate Scylla with Presto
      • Integrate Scylla with Elasticsearch
      • Integrate Scylla with Kubernetes
      • Integrate Scylla with the JanusGraph Graph Data System
      • Integrate Scylla with DataDog
      • Integrate Scylla with Kafka
      • Integrate Scylla with IOTA Chronicle
      • Integrate Scylla with Spring
      • Shard-Aware Kafka Connector for Scylla
      • Install Scylla with Ansible
      • Integrate Scylla with Databricks
    • Tutorials
  • Scylla for Administrators
    • Administration Guide
    • Procedures
      • Cluster Management
      • Backup & Restore
      • Change Configuration
      • Maintenance
      • Best Practices
      • Benchmarking Scylla
      • Migrate from Cassandra to Scylla
      • Disable Housekeeping
    • Security
      • Scylla Security Checklist
      • Enable Authentication
      • Enable and Disable Authentication Without Downtime
      • Generate a cqlshrc File
      • Reset Authenticator Password
      • Enable Authorization
      • Grant Authorization CQL Reference
      • Role Based Access Control (RBAC)
      • Scylla Auditing Guide
      • Encryption: Data in Transit Client to Node
      • Encryption: Data in Transit Node to Node
      • Generating a self-signed Certificate Chain Using openssl
      • Encryption at Rest
      • LDAP Authentication
      • LDAP Authorization (Role Management)
    • Admin Tools
      • Nodetool Reference
      • CQLSh
      • REST
      • Tracing
      • Scylla SStable
      • Scylla Types
      • SSTableLoader
      • cassandra-stress
      • SSTabledump
      • SSTable2json
      • SSTable Index
      • Scylla Logs
      • Seastar Perftune
      • Virtual Tables
    • ScyllaDB Monitoring Stack
    • ScyllaDB Operator
    • ScyllaDB Manager
    • Upgrade Procedures
      • Scylla Enterprise
      • Scylla Open Source
      • Scylla Open Source to Scylla Enterprise
      • Scylla AMI
    • System Configuration
      • System Configuration Guide
      • scylla.yaml
      • Scylla Snitches
    • Benchmarking Scylla
  • Scylla for Developers
    • Learn To Use Scylla
      • Scylla University
      • Course catalog
      • Scylla Essentials
      • Basic Data Modeling
      • Advanced Data Modeling
      • MMS - Learn by Example
      • Care-Pet an IoT Use Case and Example
    • Scylla Alternator
    • Scylla Features
      • Scylla Open Source Features
      • Scylla Enterprise Features
    • Scylla Drivers
      • Scylla CQL Drivers
      • Scylla DynamoDB Drivers
  • CQL Reference
    • CQLSh: the CQL shell
    • Appendices
    • Compaction
    • Consistency Levels
    • Consistency Level Calculator
    • Data Definition
    • Data Manipulation
    • Data Types
    • Definitions
    • Global Secondary Indexes
    • Additional Information
    • Expiring Data with Time to Live (TTL)
    • Additional Information
    • Functions
    • JSON Support
    • Materialized Views
    • Non-Reserved CQL Keywords
    • Reserved CQL Keywords
    • ScyllaDB CQL Extensions
  • Scylla Architecture
    • Scylla Ring Architecture
    • Scylla Fault Tolerance
    • Consistency Level Console Demo
    • Scylla Anti-Entropy
      • Scylla Hinted Handoff
      • Scylla Read Repair
      • Scylla Repair
    • SSTable
      • Scylla SSTable - 2.x
      • ScyllaDB SSTable - 3.x
    • Compaction Strategies
    • Raft Consensus Algorithm in ScyllaDB
  • Troubleshooting Scylla
    • Errors and Support
      • Report a Scylla problem
      • Error Messages
      • Change Log Level
    • Scylla Startup
      • Ownership Problems
      • Scylla will not Start
      • Scylla Python Script broken
    • Cluster and Node
      • Failed Decommission Problem
      • Cluster Timeouts
      • Node Joined With No Data
      • SocketTimeoutException
      • NullPointerException
    • Data Modeling
      • Scylla Large Partitions Table
      • Scylla Large Rows and Cells Table
      • Large Partitions Hunting
    • Data Storage and SSTables
      • Space Utilization Increasing
      • Disk Space is not Reclaimed
      • SSTable Corruption Problem
      • Pointless Compactions
      • Limiting Compaction
    • CQL
      • Time Range Query Fails
      • COPY FROM Fails
      • CQL Connection Table
      • Reverse queries fail
    • Scylla Monitor and Manager
      • Manager and Monitoring integration
      • Manager lists healthy nodes as down
  • Knowledge Base
    • Upgrading from experimental CDC
    • Compaction
    • Counting all rows in a table is slow
    • CQL Query Does Not Display Entire Result Set
    • When CQLSh query returns partial results with followed by “More”
    • Run Scylla and supporting services as a custom user:group
    • Decoding Stack Traces
    • Snapshots and Disk Utilization
    • DPDK mode
    • Debug your database with Flame Graphs
    • How to Change gc_grace_seconds for a Table
    • Gossip in Scylla
    • Increase Permission Cache to Avoid Non-paged Queries
    • How does Scylla LWT Differ from Apache Cassandra ?
    • Map CPUs to Scylla Shards
    • Scylla Memory Usage
    • NTP Configuration for Scylla
    • Updating the Mode in perftune.yaml After a ScyllaDB Upgrade
    • POSIX networking for Scylla
    • Scylla consistency quiz for administrators
    • Recreate RAID devices
    • How to Safely Increase the Replication Factor
    • Scylla and Spark integration
    • Increase Scylla resource limits over systemd
    • Scylla Seed Nodes
    • How to Set up a Swap Space
    • Scylla Snapshots
    • Scylla payload sent duplicated static columns
    • Stopping a local repair
    • System Limits
    • How to flush old tombstones from a table
    • Time to Live (TTL) and Compaction
    • Scylla Nodes are Unresponsive
    • Update a Primary Key
    • Using the perf utility with Scylla
    • Configure Scylla Networking with Multiple NIC/IP Combinations
  • ScyllaDB University
  • Scylla FAQ
  • Contribute to ScyllaDB
  • Glossary
  • Alternator: DynamoDB API in Scylla
    • Getting Started With ScyllaDB Alternator
    • Scylla Alternator for DynamoDB users
  • Create an issue
  • Edit this page

On this page

  • Increase Scylla resource limits over systemd
    • Issue
    • Root Cause
    • Before you start
    • Solution
    • References
Logo
Docs Contact Us About Us
Mail List Icon Slack Icon Forum Icon
© 2023, ScyllaDB. All rights reserved.
Last updated on 26 Mar 2023.
Powered by Sphinx 4.3.2 & ScyllaDB Theme 1.3.5