Question: Is Memcached Persistent?

Answer

No, by default, Memcached is not persistent. It means that the data in Memcached does not persist after a restart or shutdown of the Memcached server. When the server restarts, it starts with an empty cache.

Memcached does not provide built-in options for persistent storage directly within its native functionality. Data in Memcached is stored in-memory and is ephemeral, which means it is lost if the server restarts or crashes.

It's important to note that there are alternative solutions and tools, such as Dragonfly or Redis, that offer similar caching capabilities with built-in persistence features. If persistence is a critical requirement for your use case, you may want to consider these alternatives.

Enabling persistence in any caching system can affect performance since writing data to disk is slower than writing to memory. Additionally, most systems do not provide guarantees about the durability of the data during unexpected failures. Therefore, it's generally recommended to use caching systems like Memcached only for non-critical data where performance is more crucial than persistence.

Here's a simple example of how to start Memcached:

```
memcached -m 64 -p 11211 -u memcached -l 127.0.0.1
```

In this setup, Memcached will run with a 64MB cache, listening on port 11211, using the memcached user, and bound to localhost.

For scenarios requiring data persistence, consider exploring other solutions designed with that need in mind.