### Understand the alert

This alert indicates that the Memcached cache is running out of space and will likely become full soon, based on the data addition rate over the past hour. If the cache reaches 100% capacity, evictions may occur, resulting in a loss of cached data and decreased performance.

### Troubleshoot the alert

1. **Monitor cache usage**: Use the `stats` command in Memcached to check the current cache usage and the number of evictions. This will help you understand the severity of the issue and whether evictions are already happening.

2. **Evaluate cache settings**: Review your Memcached configuration file (`/etc/memcached.conf` or `/etc/sysconfig/memcached`) and check the cache size setting (`-m` parameter). Ensure that the cache size is set appropriately based on your system's available memory and workload requirements.

3. **Increase cache size**: If the cache is consistently running out of space, consider increasing the cache size by adjusting the `-m` parameter in the Memcached configuration file. Be cautious not to allocate too much memory, as this can cause other system processes to suffer.

4. **Optimize cache usage**: Analyze the cache usage patterns of your applications and optimize their caching strategies. This may involve adjusting the cache TTL (time-to-live) settings, using different cache eviction policies, or implementing a more efficient caching mechanism.

5. **Monitor application performance**: Check the performance of your applications that use Memcached to identify any issues or bottlenecks. If performance is degrading due to cache evictions, consider optimizing the applications or increasing cache capacity.

### Useful resources

1. [Memcached Configuration Options](https://github.com/memcached/memcached/wiki/ConfiguringServer)
