Page cache – recommended redis instance

Hello @naveen8878

Thank you for reaching out and I am happy to help!
The W3 Total Cache can use different caching methods, depending on what is available and installed on the server. This being said, it’s up to you how the Redis is configured.

As for your questions, I would recommend checking out this link for more details about Redis and how to configure it on the server and use different or multiple servers.

Thanks!

Hi,

Thank you for your reply. Guess you didn’t read through my questions. We have configured Redis and using it already from almost 10-12months and It was working fine.

Recently, from last one week we are seeing spike in redis usage which is all most 100% and earlier redis usage was at 40-50% in an average. Since redis usage is 100% and traffic is being redirected to the servers now and its stressing the servers. With this additional background, let me re-phrase my questions or ask again:

1. We need to understand from W3TC: If redis page cache keys are created based on the visitor traffic to the site? ex if we have post a,b,c,d: for each site visitor different page cache keys are created for individual posts?
2. How we can plan the capacity of the redis caching servers? currently we are using Cloud managed service. Is there any formula?
3. What might be the reason for suddenly redis servers are being utilized 100% where is there is no changes on the site.

Please let us know if any additional info is needed also is there any dedicated support from W3TC? We have 2 Pro licenses for different environments.

Looking forward for the answers.

Thanks in advance.

Hello @naveen8878

Thank you for your feedback.
So since everything was working fine it means that something happened in recent days that triggered this.
Can you please share how much memory you have on your Redis servers?

The key-value is assigned to each cached page/article.
Can you please try to restart Redis server and also, the solution here would be to flush the Redis cache.

To  Flush the Redis Cache, either the FLUSHDB or the  FLUSHALL commands could be used. FLUSHDB command deletes all the keys of the DBs selected and the FLUSHALL command deletes all the keys of all the existing databases, not just the selected one.

The syntax for the commands are:

redis-cli FLUSHDB
redis-cli -n DB_NUMBER FLUSHDB
redis-cli -n DB_NUMBER FLUSHDB ASYNC
redis-cli FLUSHALL
redis-cli FLUSHALL ASYNC

For instance, to delete all the keys of a database #4 from the Redis cache, the syntax to be used is:

$ redis-cli -n 4 FLUSHDB