When a web application has multiple content databases, it is important to understand that how SharePoint decides what content database to put a new site collection in. Recently I came across the very nice blog about how the round-robin site collection allocation works in the MOSS 2007.
According to this blog, by default SharePoint uses a round-robin approach based on the remaining site allotment. What that means is if you have 2 content databases, each with a maximum site allotment of 100 sites, then the first site collection created in the content database 1 and second site collection will be created in the content database 2, third back to content database 1, fourth to content database 2, and so on and so forth. It is important to notice that this is based on the remaining site allotment. In the example earlier, both sites had a maximum of 100 sites. If instead first content database had maximum site allotment of 110 sites and second content database had maximum site allotment of 100 sites, the first 10 site collections would go to content database 1 until both had 100 remaining, and then it would round-robin between content database 1 and 2.
In short, maximum site allocations for all the content databases for any given web application must be same for the proper configuration of the round-robin allocation.
To verify the round-robin site collection allocation of the My Site content databases, perform following steps.
- Start Central Administration Site on the MOSS farm
- Click on the Content Databases link from the Applications tab
- Make sure the right web application is selected. In this example, it is http://mysite.mossimage.local/
- Verify that “Maximum Number of Sites” settings for all the content databases are same to make sure robin-robin allocation will work