How to Expand Redis Memory on Linux: A Step‑by‑Step Guide

1. Adjust Redis Configuration

Edit the Redis configuration file (usually /etc/redis/redis.conf or /usr/local/etc/redis/redis.conf) and set the maxmemory directive to the desired limit, e.g., maxmemory 4gb. Choose an appropriate eviction policy with maxmemory-policy, such as allkeys-lru or volatile-lru. Restart Redis to apply changes:

sudo vim /etc/redis/redis.conf
maxmemory 4gb
maxmemory-policy allkeys-lru
sudo systemctl restart redis

2. Expand System Memory and Swap

When physical RAM is insufficient, create and enable a swap file to provide additional virtual memory.

# Create a 4 GB swap file
sudo fallocate -l 4G /swapfile
# If fallocate is unavailable, use dd
sudo dd if=/dev/zero of=/swapfile bs=1M count=4096
# Secure the file
sudo chmod 600 /swapfile
# Set up swap area
sudo mkswap /swapfile
# Enable swap
sudo swapon /swapfile
# Verify
swapon --show
free -h
# Persist across reboots by adding to /etc/fstab
sudo vim /etc/fstab
# Append the following line
/swapfile none swap sw 0 0

3. Tune Linux Overcommit Memory

Modify the kernel overcommit policy to allow the system to allocate more memory than physically available.

# Check current setting
cat /proc/sys/vm/overcommit_memory
# Set to 1 (always overcommit)
sudo sysctl vm.overcommit_memory=1
# Make it permanent
sudo vim /etc/sysctl.conf
# Add or modify the line
vm.overcommit_memory = 1

4. Monitor Redis Memory Usage

Use Redis CLI and standard Linux tools to observe memory consumption.

# Redis memory info
redis-cli info memory
# System memory overview
top
htop
free -h

5. Summary

Increase maxmemory in redis.conf and select a suitable eviction policy.

Add swap space to extend virtual memory when physical RAM is limited.

Adjust /proc/sys/vm/overcommit_memory to allow aggressive allocation.

Continuously monitor Redis and system memory with redis-cli, top / htop, and free.