W3TC with subdomains

Hello @damienov

Thank you for yoru question and I am happy to assist you with this.
This may depend on the modules enabled in W3 Total Cache general settings and the caching method you are using.
If for example, you are using the Disk caching method for Object Caching and DB Caching, this may, in theory, cause a lot of server resource consumption when the cache is purged.
To remedy this, it’s recommended not to use Caching for Objects and Database if caching to disk. Instead, you should consider using memory-based caching like Redis or Memcached.
Can you please share the website URL? Also please let me know which modules are enabled and which caching method you are using.
Thanks!

I only use:
– Page Cache – Disk Enhanced
– Minify – Disk
– Browser Cache – Disk

Will using memcache/Redis guaranteed to help?

• This reply was modified 3 years ago by Damienov.

Hello @damienov

Thank you for the information.
That should not cause a lot of resource consumption. Then again it depends on how many pages you have on your website.
Using memory-based caching means that the cache will be stored in memory instead of the disk.
If you are on shared hosting then Redis/Memcached may be unavailable to you. However, if you are on VPS or a dedicated server, the only thing you need to do is to install PHP Redis or PHP Memcached module and you will be able to use it in W3 Total Cache.
Thanks!

there are about 20k+ post on the site

Since Redis is not an option, memcache would be better option then?

But isn’t using memory as cache a bad idea since data stored in RAM is volatile?

Hello @damienov

Memcached is assigned a specific amount of memory. Disk cache on the other hand is managed by the OS and uses as much free memory as is available on the server. This is both good and bad, depending on how much memory is available, and how well behaved the applications on that server are. For example, you might give Memcached 2 GB of memory, but the OS might have 8 GB of free memory. The OS will use that 8 GB to cache disk access (read and write), not just of the files in your cache directory, but of all frequently accessed files.
20k+ post is a lot. If you take into consideration that the average post is 450kb if all the posts are cached… That is a lot of space consumption.
Are you by any chance using the cache preload in W3 Total Cache?
Thanks!

Yes cache preload is on with 1800 sec update interval and 10 pages per interval, Preload the post cache upon publish events is on.

will disabling any of these help?

Hello @damienov

Thank you for the information.
This means that your entire website is being preloaded. All 20k+ pages, and with the setup, you are mentioning, 10 pages are being cached over and over again every 30 minutes.
This is a lot of pages and some old files also that are waiting for the Garbage interval to kick in.
So yes disabling this would help, since only the most visited pages will be cached.
Do you need all 20k pages preloaded?
THanks!

Thanks for your help Marko, it does reduce the load just a bit. I guess I need to ask my host to activate Memcache/Redis then

• This reply was modified 3 years ago by Damienov.

Hello @damienov

Just make sure that the PHP extension is installed.
Let me know how it goes.
Thanks!