You might have heard about the “Shallow Copy” in SharePoint 2010 SP1. What does actually “Shallow Copy” does. To find it out I just used went through the description of the SP1 where I found this information.

Remote Backup Systems (RBS) and shallow copy can decrease downtime and increase efficiency by moving pointers to databases instead of moving databases.

Read further for  more information. 

And from syntax

Used to move an RBS-enabled site collection from one RBS-enabled content database to another RBS-enabled content database without moving the underlying BLOB content. If the content database has more than one RBS provider associated with it, you must specify all providers. The same providers must be enabled on the target content database and the source content database.

With other words, Shallow Copy is migration technique provide to move structured site collection data to across content database while using same RBS-data.

We still use the same command Move-SPSite by specify RbsProviderMapping parameter. The syntax is here
.

Move-SPSite [-Identity] <SPSitePipeBind> -DestinationDatabase <SPContentDatabasePipeBind> [-AssignmentCollection <SPAssignmentCollection>] [-Confirm [<SwitchParameter>]] [-RbsProviderMapping <Hashtable>] [-WhatIf [<SwitchParameter>]]

One example is here:

Move-SPSite -Identity <SiteUrl> -DestinationDatabase <DatabaseName> -RbsProviderMapping @{“<SourceProvider>”=”<TargetProvider>”}

<SiteUrl> is the URL of the site collection to be moved.                          <DatabaseName> is the name of the content database to move the site collection to
. <SourceProvider> is the name of the RBS provider in the source database. <TargetProvider> is the name of the RBS provider in the destination database.