I have installed sitecore 8 in my machine and it is working fine. Now I want to install Sitecore 7.5 on the same machine without disturbing the sitecore 8 instance. I have read that it is possible to run multiple instances of Sitecore on same machine, but how does SQL server databases are used by the two instances.
Below are the databases which got created when installed Sitecore 8.
From the db names I understand that the first 5 db names are instance/website specific, so they won’t be any problem as the new instance will name the databases as per its website name. But the last two databases are named generically. So if I install the sitecore 7.5, will it use the same two databases - ‘ReportServer’, ‘ReportServerTempDB’?. If so will it append the data of the new website to existing data or will it overwrite? In both the cases will it affect the two websites or they run without any issues?
Also, both these two versions of Sitecore uses MongoDB for xDB (Experience Database). How is MongoDB shared between these instances?
FYI, I have made MongoDB to run as Windows service as in this tutorial.