Choosing PHP Session and Cache Storage: Files vs Redis vs Memcached for WordPress and Laravel

When you want to speed up a WordPress or Laravel site, most people start with PHP version, PHP-FPM settings, or MySQL tuning. But there is a quieter decision that often decides how far you can scale: where you store PHP sessions and application cache. Files, Redis, and Memcached all solve the same problem in different ways, and choosing the wrong one for your traffic pattern can create random logouts, slow checkouts, or cache misses at the worst possible time. In this guide, we will look at how each storage option behaves under real load, what it means for WordPress and Laravel specifically, and how to align your choice with the hosting environment you run on at dchost.com. By the end, you will have a practical checklist to decide when files are enough, when Redis is worth the complexity, when Memcached still shines, and how to configure each option cleanly on a VPS, dedicated server, or colocation setup.

Sessions vs Cache: What Problem Are You Solving?

Before comparing storage backends, it helps to separate two concepts that are often mixed in the same sentence: sessions and cache.

• PHP sessions: Per-user data stored between requests. Think login state, cart contents, multi step form progress. They must be available and consistent for that user, but not necessarily forever.
• Cache: Data that is expensive to compute or fetch, but relatively cheap to lose. Think rendered fragments, database query results, API responses, or WordPress transients.

In WordPress, core itself barely uses PHP sessions, but many plugins and especially WooCommerce rely on them. Caching shows up at several layers: full page cache, object cache, and transients. In Laravel, sessions and cache are first class citizens with configurable drivers; the same Redis cluster can serve sessions, cache, and queues.

Once you see sessions and cache as separate concerns, the trade offs between files, Redis, and Memcached become much clearer.

Option 1: File Based Sessions and Cache

By default, PHP stores sessions in the file system via the files handler. Each visitor gets a small file on disk keyed by session ID. Laravel can also store cache data on disk using the file driver. This is simple and works out of the box on almost any hosting plan.

When File Storage Is Good Enough

File based storage is not always the enemy. It is often the right choice in these situations:

• Single server, modest traffic: A corporate site, a small blog, or an internal dashboard with a few hundred active sessions at most.
• Shared hosting: You cannot install Redis or Memcached, but you still want stable sessions. The default PHP session files usually work fine if the disk is not overloaded.
• Development and staging: Simple, predictable behaviour is more important than maximum speed.

On a tuned VPS with fast NVMe storage, file based sessions can sustain more load than many people expect. If you already optimized PHP-FPM settings for WordPress and WooCommerce and have decent OPcache, file sessions may not be your first bottleneck.

Common Bottlenecks and Pitfalls With Files

File based sessions have three main issues as your site grows:

• Locking overhead: PHP locks the session file while a request is working with it. Long running requests can block other requests from the same user and sometimes from others, depending on configuration.
• Slow or overloaded disks: On busy shared hosting or on HDD based servers, repeated disk access for thousands of session files can create noticeable latency.
• Multi server setups: If you scale WordPress or Laravel horizontally behind a load balancer, each server needs access to the same session path, usually via NFS or another shared file system. This easily becomes a single point of failure and a performance bottleneck.

For caching, file storage is even less attractive. Cache by definition is accessed frequently; hitting the disk for every cache read or write burns I/O and increases latency compared to in memory stores.

Option 2: Redis for Sessions and Cache

Redis is an in memory key value database that can persist data to disk and supports rich data structures. In the PHP world it has become the default answer whenever performance is mentioned, and often for good reason.

Why Redis Fits PHP Workloads So Well

• Everything in memory: Reads and writes are extremely fast compared to disk based storage, especially under load.
• Atomic operations: Redis can increment counters, update hashes, and manage sets in a single atomic step, which is great for rate limiting, feature flags, and queues.
• Flexible persistence: You can choose snapshot based persistence (RDB), append only file (AOF), both, or none, depending on how much you value durability versus performance.
• Network accessible: Multiple PHP workers, containers, or servers can share the same Redis instance easily, which solves the multi server session problem without NFS.

This is why many of our customers on VPS and dedicated servers use Redis simultaneously for sessions, cache, queues, and even real time counters.

Redis for WordPress: Object Cache, Transients, and Sessions

In modern WordPress setups, Redis usually appears in three roles:

• Persistent object cache: WordPress can store query results and expensive computations in Redis, dramatically reducing MySQL load on busy sites. We walk through the full setup in our guide on WordPress object cache with Redis or Memcached.
• Transients backend: Plugins that use transients benefit from Redis because they are no longer limited by database size or slow options table lookups.
• Sessions for plugins and WooCommerce: When you run more than one web server, storing PHP sessions in Redis avoids sticky sessions at the load balancer and works cleanly with autoscaling.

For high traffic WooCommerce stores, we almost always recommend Redis object cache plus Redis based sessions once you move to a VPS or dedicated server at dchost.com. Combined with proper PHP-FPM tuning and NVMe disks, this setup can handle spikes much more gracefully.

Redis for Laravel: Sessions, Cache, and Queues

Laravel has first class Redis support. In config/cache.php, you can set the default driver to redis, and in config/session.php you can choose session driver redis as well. The framework then handles connections and serialization for you.

Typical Laravel patterns with Redis include:

• Sessions in Redis: Removes file locking problems and makes horizontal scaling much easier.
• Cache in Redis: Fast access to configuration data, query results, and custom application caches.
• Queues in Redis: Many teams start with Redis queues before moving to more specialised tools.

Our article The Laravel production tune up we do on every server explains how Redis fits together with PHP-FPM pools, OPcache, and Horizon in a real world deployment.

Redis Drawbacks and Gotchas

Redis is powerful, but it is not magic. You should be aware of a few trade offs:

• Needs RAM: Everything lives in memory. If you undersize RAM, the kernel will start swapping, and performance collapses.
• Persistence is configurable, not automatic: Depending on your RDB and AOF settings, you can lose some recent writes on crash. This is usually acceptable for cache, but more sensitive for sessions.
• Eviction policy matters: If you use the same Redis instance for sessions and cache, a bad maxmemory and eviction configuration can cause user sessions to be evicted under pressure. We go deeper into TTL and eviction strategy in our Redis vs Memcached tuning playbook for WordPress and WooCommerce.

On larger WordPress and Laravel projects, we often recommend either separate Redis databases or separate Redis instances for sessions, cache, and queues to avoid interference.

Option 3: Memcached for Sessions and Cache

Memcached is another in memory key value store, older than Redis and simpler in scope. It focuses on being a very fast, distributed cache for small values, without persistence or advanced data structures.

Where Memcached Still Makes Sense

Memcached is a strong candidate when:

• You only need a cache, not a general purpose data store: No need for lists, sets, or scripts. Just keys and values with TTLs.
• Absolute simplicity is a benefit: Fewer features mean fewer footguns. For some teams, this is an advantage.
• You want to spread cache across multiple nodes: Memcached clients can distribute keys across several servers using consistent hashing.

In many benchmarks, Memcached and Redis are similar for simple get and set patterns. The choice then comes down to ecosystem and features.

Memcached Limitations You Need to Know

Memcached is intentionally limited, which matters for your design:

• No persistence: If the process restarts, all data is gone. That is acceptable for cache, risky for sessions.
• No built in replication or clustering: High availability needs to be handled at the client or infrastructure level.
• Maximum item size: By default, each value is limited to a certain size (often 1 MB). Storing huge objects is not a good fit.

For these reasons, we rarely recommend Memcached for session storage on critical shops or SaaS applications. For pure WordPress object cache or Laravel cache on a single server, it can still be a fine option, especially if your team is already experienced with it.

Files vs Redis vs Memcached: Comparison by Criteria

Here is a high level comparison of the three options across key dimensions.

Choosing Storage for Common WordPress Scenarios

1. Small Blog or Company Site on Shared Hosting

If you run a classic blog or a brochure site with a page builder, low to medium traffic, and a single hosting account, you do not need to rush into Redis.

• Leave PHP sessions on files, the default.
• Use a good page cache plugin or LiteSpeed Cache if your plan supports it. Our hosting performance guide for Elementor, Divi and other builders explains how to size CPU and RAM correctly.
• Make sure you are on a plan with SSD or NVMe storage so session file I/O stays fast.

In this scenario, the main gains usually come from PHP-FPM and OPcache tuning, CDN usage, and image optimisation rather than switching session storage.

2. Growing WooCommerce Store on a VPS

Once your store has consistent traffic, campaigns, and peak hours, file based sessions and database backed transients become a real limitation. Here we regularly recommend:

• Sessions in Redis: Configure PHP to use Redis as session handler so all checkout and account sessions live in memory.
• Persistent object cache in Redis: Offload expensive WooCommerce queries from MySQL. Combine this with the tuning ideas in our server side secrets that make WordPress fly.
• Page cache at web server or CDN level: This reduces PHP work for anonymous traffic; our guide on Nginx microcaching for PHP shows what is possible even on a single VPS.

At this stage, moving to Redis is usually more impactful than changing hardware alone. On dchost.com VPS plans with NVMe storage, a properly tuned Redis backed WooCommerce store can serve significantly more concurrent users with lower TTFB.

3. WordPress Behind a Load Balancer or Reverse Proxy

As soon as you have more than one web server behind a reverse proxy or load balancer, file based PHP sessions become a liability. You either need sticky sessions at the balancer or a shared file system, both of which create operational friction.

The cleaner pattern is:

• Use Redis for PHP sessions, reachable from all app servers.
• Store WordPress object cache in the same Redis cluster, but ideally in a separate logical database or instance.
• Place Nginx or another proxy in front; if you are curious about minimal setups, we demonstrate a simple architecture in our Nginx reverse proxy and load balancer guide.

For even higher resilience, you can run Redis with Sentinel and replicas. We cover that in detail for WordPress in our high availability Redis guide.

Choosing Storage for Common Laravel Scenarios

1. Internal Tools and Admin Panels

For small internal applications with limited concurrency, Laravel sessions and cache on files or database can be perfectly acceptable:

• Set the session driver to file and the cache driver to file or database.
• Keep everything on a single VPS or dedicated server to avoid cross node session issues.
• Focus optimisation on PHP-FPM, OPcache, and database indexes.

You can always switch to Redis later with a configuration change once you feel real pain from session file locking or slow cache reads.

2. Public APIs and Mobile Backends

Public APIs often use stateless authentication with JWTs or access tokens, which minimises reliance on server side sessions. However, they can hit the cache very heavily for rate limiting, configuration data, feature flags, and aggregated responses.

In this pattern, Redis is a natural fit:

• Use Redis as the cache driver for low latency lookups.
• Use Redis to implement rate limiting buckets and counters.
• Optionally keep admin sessions in Redis as well if you have an admin UI.

Because these workloads are cache heavy, Memcached can also work, but Redis usually wins thanks to better tooling and more expressive operations.

3. High Traffic SaaS With Background Jobs

For busy SaaS platforms built on Laravel with queues, broadcasting, and multiple web workers, we rarely see file based sessions in production. A typical robust design looks like this:

• Laravel sessions in Redis, with a reasonable TTL and secure cookie settings.
• Application cache in Redis, sometimes on a separate instance or logical database.
• Queues in Redis or a dedicated queue system, monitored via Horizon.
• App servers scaled horizontally behind a load balancer, stateless except for Redis and the database.

This is effectively the pattern we describe in our no drama Laravel on VPS deployment playbook. On dchost.com infrastructure, you can start with a single Redis instance on your main VPS and later move to a separate VPS or dedicated Redis node without changing application logic.

Quick Decision Checklist

If you are uncertain, this simple checklist often points in the right direction:

• Single server, modest traffic, no queues: Files for sessions, no dedicated cache needed at first.
• Single server, but WooCommerce or busy Laravel app: Redis for cache and optionally sessions; monitor RAM usage.
• Multiple app servers or containers: Redis for sessions is strongly recommended; Memcached or Redis for cache.
• Mission critical store or SaaS: Redis for sessions and cache, with high availability and backups; avoid Memcached for sessions.

Practical Configuration Tips on a VPS or Dedicated Server

1. PHP, FPM, and OPcache Still Matter

Switching to Redis will not fix a misconfigured PHP environment. Before or alongside changing session and cache storage, make sure:

• PHP version is modern (PHP 8.x) and compatible with your application. Our PHP 8.x upgrade checklist for WordPress and Laravel can be a good reference.
• PHP-FPM pools are tuned to match your CPU and RAM, as explained in our dedicated PHP-FPM settings guide.
• OPcache is enabled and sized correctly, so PHP does not recompile scripts on every request.

Only after these basics are in place does changing session and cache storage show its full benefit.

2. Baseline Redis Settings for Sessions and Cache

On a typical VPS for WordPress or Laravel, a pragmatic Redis configuration might include:

• Dedicated instance or database for sessions: Avoid eviction of sessions due to heavy cache usage.
• maxmemory set to a safe fraction of RAM: For example, 50 to 70 percent of total RAM, depending on other services.
• maxmemory policy: Use an appropriate eviction policy such as allkeys lru for pure cache, but be careful when sessions are involved.
• Persistence: For sessions, consider enabling at least periodic snapshots (RDB) to reduce impact of a crash.

Monitor Redis memory usage, key counts, and latency. If you already use tools like Prometheus and Grafana for your VPS, add Redis exporters and alerts alongside CPU and disk metrics.

3. Memcached Sizing and Key Strategy

If you choose Memcached for cache, keep these points in mind:

• Allocate enough RAM to Memcached, but leave room for PHP-FPM, MySQL, and the OS.
• Use clear, namespaced keys (for example, prefixing with app or environment name) to avoid collisions when multiple apps share the same instance.
• Remember that Memcached may evict keys under memory pressure without warning; design your application to treat cache misses as normal.

For WordPress, switching from database backed transients to Memcached based object cache can significantly reduce database load, even without touching the rest of the stack.

4. Monitoring and Troubleshooting

New storage layers can introduce new failure modes. Some practical tips:

• Log and alert on Redis or Memcached connection failures from PHP.
• Watch for spikes in PHP session start times or Laravel response times after enabling a new driver.
• Monitor VPS resources; our guide on monitoring VPS resource usage with htop, iotop, Netdata and Prometheus is a good starting point.

If performance seems worse after switching to Redis or Memcached, double check that PHP is using the expected driver, that there are no firewall issues causing timeouts, and that the instance has enough RAM to stay out of swap.

Putting It All Together on dchost.com Infrastructure

From our perspective at dchost.com, the best setups are the ones that evolve gradually instead of jumping to complexity from day one. A realistic progression looks like this:

• Start on shared hosting with file based sessions for a small WordPress or Laravel project.
• Move to a VPS with NVMe storage when you need more control over PHP-FPM, OPcache, and dedicated Redis or Memcached.
• Add a separate Redis instance or server once your store or SaaS outgrows a single box and you need high availability or more predictable performance.
• For very large projects, use dedicated servers or colocation with separate nodes for database, cache, and application, each tuned for its role.

At every stage, the choice between files, Redis, and Memcached is less about popularity and more about your traffic profile, failure tolerance, and operational experience. Files are simple and robust for small sites. Redis gives you headroom and flexibility once you invest a little time in configuration. Memcached remains a solid option for simple caching when loss is acceptable.

If you are planning a migration or a new project on dchost.com and are unsure how to design session and cache storage, feel free to sketch your current or planned architecture and map it against the scenarios in this article. Combine that with the deeper dives we linked, especially on WordPress object caching and Laravel production tuning, and you will have a clear, realistic plan for performance that does not depend on guesswork.