Are there any advantages of placing a Apache solr server and your lamp/lemp stack on the same EC2 instances?
Or is there really nothing wrong with it all given that it's on an EC2?
Or if there are disadvantages why would you want your apache solr server and lamp/lemp stack seperated into different instances?
The team does plan on scaling this application; so i'm looking to make the best architectural decision based on scalability.
There is nothing special or magic about EC2 instances. They are just a linux server, plain and simple.
Ask this question about co-locating any applications on any server, physical or virtual, and the answer will be the same: if performance is ok, then go for it. If performance suffers due to resource contention, then separate the apps.