Powershell to Move a Site Collection to a new Content Database

Problem: I have several site collections inside a single content database.  The content database is growing rapidly.  Backup and restore is fairly slow and SQL can start slowing down if the db is large enough.

Hypothesis: Create at least additional content db, move specific site collections to the new Content database.  I was surprised that moving site collections to content databases is not in the Central Admin (CA) UI.

Resolution: Create an additional content database either using PowerShell (PS) or the UI namely:
1.> CA > Application Management > Manage Content Databases > Add a Content Database (I called my content database "WSS_Content_Empty").
2.> Move the Site collection to the new content database using PS

3.> Check the database has been moved in CA

More Info:
http://technet.microsoft.com/en-us/library/cc825328.aspx

Set New Content Database using CA Only:

1. UI only option to achieve the same result would be to create the new content database using CA as shown above. 
2. Next using CA go to "Manage Content Databases", select the old/existing content database and set it to offline (This means that you can't add new content databases, existing site collections are still available).

3. Adding a new Site Collection will now use the new/next content database that is ready/online.   

End of Post

Backup and Restore Powershell commands:

if ((Get-PSSnapin "Microsoft.SharePoint.PowerShell" -ErrorAction SilentlyContinue) -eq $null) {

    Add-PSSnapin "Microsoft.SharePoint.PowerShell"

}

cls

Backup-SPSite -Identity 'http://my.demo.dev/sites/kbtest' -Path C:\Projects\Backup\test.bak -Force -NoSiteLock -UseSqlSnapshot -Verbose

Restore-SPSite -Identity 'http://my.demo.dev/sites/newkbtest' -Path C:\Projects\Backup\test.bak -Force -Verbose