I’m thinking about getting a vps to experiment some stuff.
I have three websites that I want to migrate, completely unrelated.
From a resource point of view I assume a multisite installation is cheaper than three different installation, am I wrong? is a multisite one good if the site are totally different in plugins, admins,themes and so on?
also, is a multisite (of 3 identical site) more expensive han a singlesite 3 times bigger? why is that?
thank you
I am not aware of any significant performance differences between using a multi-site and several distinct instances of WordPress. Nor have I heard of performance being an incentive or disincentive to using a Multi-Site.
I cannot give you a definitive answer as to whether or not there is a performance difference, but I’d be willing to bet it is negligible.
The real reason you use a multi-site is to make management easier. It’s also great if you need to share users across multiple sites; a multi-site has a single user table, but separate tables for posts, options, categories, etc.
Regarding your other question:
I’ll assume that by bigger you mean more posts.
In terms of storage there is not going to be a significant difference. In terms of performance there can be.
Multi-sites have separate tables for posts for each individual site. When you’re viewing an individual site within a multi-site, queries are only being run on one of those tables. With respect to performance, this question boils down to:
The answer to that seems obvious. However, it is important to note that database performance is not linear with respect to database size. Queries on a site A are not going to be three times faster than site B (typically).
The comparison doesn’t really say anything about multi-sites. There is no way to break the larger site up into several sites in a multi-site and there is no way to combine the multi-site sites into a large single site.
Update:
Assuming the separate instances are installed on the same server, it may be somewhat harder to attack all three sites compared with a single multi-site. However, once someone is able to execute their own code on your server, it is trivial to expand an attack to other sites on the same server.
While it may be a bit harder for an attacker to compromise three separate instances of WordPress, it is also harder to secure those separate instances. With a multi-site you can easily deploy security measures across all of your sites.