Hosting Web and DB on 2 different KVMs too slow

[DrPit]

Hello,

I have noticed that hosting a site on 2 different kvms in the same node is much slower than hosting the db inside a single kvm
What could I check to see what causing this problem

 

[wolfgang]

Hi,

I assume you are taking about SQLDB?

This is a normal behavior if the two DB are on the same physical disk.
That happens because a DB will optimize the io and when you have 2 of them they don't know about the io of the outer DB.
So the can't really optimize the io.

 

[DrPit]

Hi,
I have just one DB Server and one Web Server with no load both of them have external IPs
and I tested the same site on a single VM including both db server and web server no load again
I use a SSD Disks which eliminates any io problem at my load

 

[czechsys]

Well, you forgot one thing. Having things "locally" is in 99% cases faster than having things over network. And even if you have both VMs on same node, they works through network, in this case "virtual" network is faster than physical, but still limited.