Installing Memcached Across Platforms

On Debian/Ubuntu
Update your package index and install the server with client utilities.

sudo apt update
sudo apt install memcached libmemcached-tools

To enable and immediately launch the service:

sudo systemctl enable --now memcached

On RHEL/CentOS
Refresh your repository metadata and install the package.

sudo yum update
sudo yum install memcached

After the installation, start it with systemd:

sudo systemctl enable --now memcached

On macOS via Homebrew
Ensure Homebrew is on the system, then pull in the formula.

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
brew update && brew install memcached

Launch the daemon in the background:

memcached -d

On Windows
Obtain a prebuilt binary from memcached-win64 and extract it. After adding the folder to your PATH, register and start the service:

memcached.exe -d install
memcached.exe -d start

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Runtime Parameters and Configuration Files

Memcached behavior is adjusted through command-line flags or a configuration file. Essential flags include:

• -m : allocated cache memory in megabytes
• -p : TCP listening port (default 11211)
• -c : maximum simultaneous connections (default 1024)
• -u : system user to drop privileges to

Command-line invocation

memcached -d -m 1024 -p 11211 -u memcache -c 2048

File‑based configuration

Create a file such as /etc/memcached.conf:

# Memory ceiling (MB)
-m 1024
# Network port
-p 11211
# Connection cap
-c 2048
# Runtime user
-u memcache

Point the daemon at the file:

memcached -d -f /etc/memcached.conf

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Setting Up a Persistent System Service

For automatic startup, define a systemd unit.

Unit file — /etc/systemd/system/memcached.service

[Unit]
Description=Memcached cache daemon
After=network.target

[Service]
User=memcache
ExecStart=/usr/bin/memcached -m 512 -p 11211 -u memcache -c 1024
ExecStop=/bin/kill -s QUIT $MAINPID
Restart=on-failure

[Install]
WantedBy=multi-user.target

Reload the manager and activate the unit:

sudo systemctl daemon-reload
sudo systemctl enable --now memcached

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Troubleshooting Common Issues

Service fails to start
Inspect the logs (often /var/log/memcached.log or journalctl -u memcached). Verify port availability with ss -tlnp | grep 11211.

Memory exhaustion
Increase the -m value and ensure the OS has sufficient free RAM. Restart the daemon to apply the change.

Connection overload
Raise the -c limit. Monitor peak connections and adjust accordingly.

memcached -c 4096

Permission issues
Confirm the runtime user owns the working directory and log paths.

sudo chown -R memcache:memcache /var/log/memcached

Network restrictions
Open port 11211 in the local firewall.

sudo ufw allow 11211/tcp   # Ubuntu
# Or firewalld
sudo firewall-cmd --add-port=11211/tcp --permanent
sudo firewall-cmd --reload

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Practical Configuration Recipes

Development single‑instance

-m 256
-p 11211
-c 1024
-u nobody

Production‑grade setup
Bind to localhost, anable verbose logging, and fine‑tune slab allocation.

-m 4096
-p 11211
-c 4096
-u memcache
-l 127.0.0.1
-vv
-logfile /var/log/memcached.log
-I 2m
-t 4

Multi‑node environment with HAProxy
Two backend instances with a round‑robin frontend.

Node 10.0.0.1

-m 1024
-p 11211
-c 2048
-u memcache
-l 10.0.0.1

Node 10.0.0.2

-m 1024
-p 11211
-c 2048
-u memcache
-l 10.0.0.2

HAProxy backend stanza

backend memcache_cluster
  balance roundrobin
  server cache1 10.0.0.1:11211 check
  server cache2 10.0.0.2:11211 check