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diff --git a/health/guides/memcached/memcached_cache_fill_rate.md b/health/guides/memcached/memcached_cache_fill_rate.md new file mode 100644 index 000000000..ec276b3a7 --- /dev/null +++ b/health/guides/memcached/memcached_cache_fill_rate.md @@ -0,0 +1,41 @@ +### Understand the alert + +This alert, `memcached_cache_fill_rate`, measures the average rate at which the Memcached cache fills up (positive value) or frees up (negative value) space over the last hour. The units are in `KB/hour`. If you receive this alert, it means that your Memcached cache is either filling up or freeing up space at a noticeable rate. + +### What is Memcached? + +Memcached is a high-performance, distributed memory object caching system used to speed up web applications by temporarily storing frequently-used data in RAM. It reduces the load on the database and improves performance by minimizing the need for repeated costly database queries. + +### Troubleshoot the alert + +1. Check the current cache usage: + +You can view the current cache usage using the following command, where `IP` and `PORT` are the Memcached server's IP address and port number: + +``` +echo "stats" | nc IP PORT +``` + +Look for the `bytes` and `limit_maxbytes` fields in the output to see the current cache usage and the maximum cache size allowed, respectively. + +2. Identify heavy cache users: + +Find out which applications or services are generating a significant number of requests to Memcached. You may be able to optimize them to reduce cache usage. You can check Memcached logs for more details about requests and operations. + +3. Optimize cache storage: + +If the cache is filling up too quickly, consider optimizing your cache storage policies. For example, you can adjust the expiration times of stored items, prioritize essential data, or use a more efficient caching strategy. + +4. Increase the cache size: + +If needed, you can increase the cache size to accommodate a higher fill rate. To do this, stop the Memcached service and restart it with the `-m` option, specifying the desired memory size in megabytes: + +``` +memcached -d -u memcached -m NEW_SIZE -l IP -p PORT +``` + +Replace `NEW_SIZE` with the desired cache size in MB. + +### Useful resources + +1. [Memcached Official Site](https://memcached.org/) |