SharePoint 2013 Deferred Site Collection Upgrade

Today, the next generation of Microsoft Office, Microsoft Office 365 Enterprise and SharePoint 2013 were all made available via technical preview. As a SharePoint MVP, I’ve been under the NDA curtain, so it’s great to finally have a bunch of news in out in the wild so we can all talk about the next release.

The differences between SharePoint 2010 and SharePoint 2013 are outlined in this TechNet post: Changes from SharePoint 2010 to SharePoint 2013 Preview. I wanted to clarify something that I believe could be confusing to SharePoint administrators as they first hear about the new “deferred site collection upgrade option.”

Here is the section about SharePoint 2013 upgrade:

Visual upgrade

Description: The visual upgrade feature in SharePoint Server 2010 is not available in SharePoint 2013 Preview. For the upgrade from Office SharePoint Server 2007 to SharePoint Server 2010, you could choose to use the visual upgrade feature to give site collection owners and site owners the opportunity to preserve the previous user interface temporarily while still upgrading the infrastructure and databases, site collections, and features to the latest version. This allowed site collection owners and site owners to update customizations to work in the new user interface. Once the database and site collection upgrade was complete, the user had the option to upgrade the user interface on a more granular level of the website (SPWeb object).

Reason for change: The visual upgrade feature is replaced with deferred site collection upgrade. The site collection upgrade process is not reversible. The deferred site collection upgrade is a more comprehensive upgrade process than visual upgrade.

Visual upgrade preserved only the old master pages, CSS files, and HTML files. Deferred site collection upgrade preserves much more, including SPFeature functionality. To achieve the deferred site collection upgrade, major changes in the architecture were required, including the removal of visual upgrade.

With deferred site collection upgrade, you can continue to use the UI from the previous version (SharePoint Server 2010) more seamlessly than is possible with visual upgrade. The master page, CSS, JScript, and SPFeatures will remain in SharePoint Server 2010 mode. One key difference is that the granularity of upgrading the user interface is per site collection (SPSite) instead of site (SPWeb). Users can still preview their site in the new SharePoint 2013 Preview user interface before committing. However, this is accomplished by creating and upgrading a temporary copy of their site collection instead of a preview in the existing instance of the site collection. The reason for previewing a copy of the site collection is because of the complexity of what occurs during site collection upgrade. Once a site collection is upgraded, it cannot be rolled back. Therefore, performing a preview would not be possible except in a copy of the site collection.

Migration path: Site collection administrators who are using visual upgrade to continue to use SharePoint Server 2007 must move to the SharePoint Server 2010 user interface before upgrading to SharePoint 2013 Preview. After the content database is upgraded, users can use deferred site collection upgrade to continue to use the SharePoint Server 2010 experience for their site collections. Site collection administrators can be notified by their farm administrator when a site collection is ready for upgrade and the site collection administrators can then choose to either perform the upgrade of their site collection or optionally first preview the new functionality in a temporary copy of their site collection.

Any SharePoint user interface might have dependencies on visual upgrade. The main dependency was getting the user interface version and then outputting the correct user interface (new or legacy). The visual upgrade API feature is updated so that the user interface version is remapped to the new site collection compatibility level property. This returns the same information about which version the site uses as before. Therefore, dependent code does not need to change.

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There is no doubt that the new deferred site collection upgrade is a great improvement; rather than just the look and feel of the site staying in the previous version (as you could do in SharePoint 2010), the actual schema can be left in the old version of SharePoint and virtually everything (read: customizations) will continue to function as before. This clearly means that less work is done and the upgrade process will be faster; albeit with the requirement to finish the site collection upgrade at some later point.

For anyone looking at this new feature and thinking about their upgrade or migration to SharePoint 2013, it’s important to differentiate deferred upgrade from a gradual or granular upgrade. I’m sure some people will refer to deferred as gradual, and I can see how that could be just a semantic argument. However, it’s clear that there is a difference between a granular migration and a deferred migration. Although the deferred site collection upgrade allows a content database to be upgraded without the underlying schema being upgraded, it is still scoped at the database level. If you are looking to migrate or upgrade part of your SharePoint 2010 implementation to SharePoint 2013, the new deferred upgrade is not meant to enable that scenario.