load balancing - Running multiple user-heavy sites from a single codebase -

load balancing - Running multiple user-heavy sites from a single codebase -

i have series of 15 sites, running off of 15 instances of same codebase , spread on 4 dedicated servers. each site differs slightly, different theme , settings , translations changed match instance, otherwise identical.

here's illustration of mean:

server 1 site 1 site 2 site 3 site 4 server 2 site 5 site 6 site 7 site 8 server 3 site 9 site 10 site 11 site 12 server 4 site 13 site 14 site 15

when there 1 server, easy manage now, 15 (and growing) instances of different variations of site, it's becoming nightmare manage , update.

i'm rewriting codebase , prefer consolidate sites one, know single server much load slow scheme significantly.

i need way can consolidate info without killing performance. thinking run database servers on 2 of servers, cache (like varnish) on one, , nginx on 1 doesn't sense scaleable.

is there improve way i'm missing?

hosting

i recommend using/hiring paas (platform service) or iaas (infrastructure service). way else manage hardware , services , have worry code. great thing platform scale application need. (but bad code -> bad performance cost alot of money though)

take @ aws example: http://aws.amazon.com/

updating

also recommend using version command update sites.

personally prefer git (because of branches , local repository). create branch every client in custom layout code. when deveop on main branch can merge other branches , pull on client sites.

though suggest keeping custom code seperated basic code! (this should split).

so create script git pull , you'll have automated update-proces! (make can run administrator back-end in site, , set!)

hope helps!

word of advise: work in different branch production branch, , release: merge production branch when have stable version.

load-balancing server